Читать книгу The Handy Geography Answer Book - Paul A Tucci - Страница 13
ОглавлениеHow much of the Earth is covered by water?
About 71% of the surface area of the Earth is covered by water. Oceans hold 96.5% of the Earth’s water. The other 29% of the Earth is land, located primarily in the Northern Hemisphere. If you look at a globe, you’ll notice that the Southern Hemisphere has a much larger surface area covered with water.
How much is the sea level rising?
Scientists believe that sea levels are rising by approximately .12 inches (3.05 mm) per year. The rising sea levels have been more extreme during the past century because of the increase in temperature of the world’s oceans as well as the gradual melting of ice in the Earth’s polar regions. The recent increase in sea levels are more extreme than over the past one thousand years.
What countries are threatened the most from rising sea levels and may cease to exist in the twenty-first century?
Many of the world’s small island nations are concerned about the rising sea levels. Lowlying island nations of the Pacific and Indian oceans are most at risk, most notably Tuvalu, the Maldives, Palau, and Micronesia. Other candidates for severe flooding and reclamation of coastal land by the impending sea include Bangladesh, India, Thailand, Vietnam, Indonesia, and China, affecting the lives of hundreds of millions of people.
How much land disappears when the sea level rises?
Scientists believe that as the seawater rises by 0.04 inches (1 millimeter), the shoreline disappears by 4.9 feet (1.5 meters). This means that if the sea level rises by 3.28 feet (1 meter), the shorelines will extend another 1 mile (1.6 km) inland.
What is a nautical mile?
Used for measuring ocean-based distances, a nautical mile is equivalent to approximately 6,076 feet (1,852 meters) or 1.15 miles (1.85 km). The speed of ships is measured in knots. One knot is equivalent to one nautical mile per hour.
What is the average depth of the Earth’s oceans?
The average depth of the Earth’s oceans is approximately 14,000 feet (4,267.2 meters) deep.
What percentage of the Earth’s surface is covered by water?
Approximately 70.8% of the Earth’s surface is covered by saltwater. Although we have but one giant, interconnected ocean covering the planet, we divide it into large sections called oceans and smaller bodies of water called seas.
How is water distributed on the Earth?
The oceans contain approximately 97% of all of the world’s water. Of this ocean water, 96% is saltwater or saline. The other 4% is comprised of freshwater flows, ice, snow, and precipitation. Of the 3% of nonocean water, approximately 69% of that is frozen in the form of glaciers and ice caps; 90% of this water is in Antarctica, and about 9% is in Greenland. What remains is the source of most of the water that we use each day. Of this useful water, 30% is merely groundwater, and .3% of this water is actually found in rivers and lakes. So less than 1% of all available fresh water on the planet can be found in rivers and lakes. Only .1% of water is found in the atmosphere.
What are the names of the oceans and seas?
The five largest bodies of water are named the Atlantic Ocean, the Pacific Ocean, the Indian Ocean, the Arctic Ocean, and the Southern Ocean. Each of the world’s oceans have numerous seas, including the Baltic Sea, the Mediterranean Sea, the Greenland Sea, the Ross Sea, the Andaman Sea, and the Coral Sea.
How many seas are landlocked and not connected to the world’s oceans?
There are four seas that are completely surrounded by land: the Aral Sea, the Caspian Sea, the Dead Sea, and the Salton Sea.
What is so dead about the Dead Sea?
The Dead Sea was considered to be dead because of its high salinity (at 34.2%, which is approximately 9.6 times more salty than the world’s oceans). So aquatic life cannot survive in such conditions. But there are several other places that have more salinity than the Dead Sea, including Lake Vanda (Antarctica), Lake Assal (Djibouti), Lagoon Garabogazköl (Caspian Sea), and many lakes in the McMurdo Dry Valleys (Antarctica), where the salinity in each of them has been measured at more than 40%.
What are trenches?
Trenches are deep, “v”-shaped depressions on the Earth’s surface, lying in the deepest parts of the Earth’s oceans, mostly in the Pacific Ocean. They are caused by subduction, where tectonic plates collide, pushing one heavier, older plate underneath a relatively less dense, newer plate, causing the formation of deep trenches, mountains, earthquakes, and volcanic islands.
The deepest point in the oceans of the planet is the Mariana Trench in the South Pacific Ocean. The above map also shows where the Challenger Deep is located, with a depth of 35,814 feet (10,916 meters).
What island did Robinson Crusoe shipwreck on?
Daniel Defoe based his novel Robinson Crusoe on the real-life story of Alexander Selkirk. Selkirk was an English sailor who had an argument with the captain of his ship and asked to go ashore on the island of Más a Tierra (also known as Robinson Crusoe Island or Isla Robinson Crusoe), about 400 miles (644 kilometers) west of Santiago, Chile, in the South Pacific Ocean. Selkirk was stranded on the island from 1704 to 1709, when he was rescued by another English ship.
What are some of the deepest points in the oceans?
Lying deep below the Pacific Ocean, about 200 miles (322 km) south of the island of Guam, is the Marianas Trench (also known as the Mariana Trench), which is 1,554 miles (2,550 km) long and 44 miles (71 km) wide. The deepest point of the Marianas Trench is named Challenger Deep at 35,814 feet (10,916 meters), first discovered by the HMS Challenger in 1875. In the Atlantic Ocean, the Puerto Rico Trench is 28,373 feet (8,648 meters) below the surface. In the Arctic Ocean, the Eurasia Basin at the Litke Deep is 17,881 feet (5,449 meters) deep. The Java Trench or Sunda Trench in the Indian Ocean is 25,344 feet (7,725 meters) deep. Another deep point of note in the Pacific Ocean is Monterey Canyon off the coast of northern California. It is about 95 miles (153 km) long and 11,800 feet (3,600 meters) deep. The cold waters generated in the trench create a perfect environment rich in foods that support a diverse range of wildlife.
In comparison to all of these ocean canyons, the most famous land canyon—the Grand Canyon in Arizona—is 277 miles (446 km) long and 6,000 feet (1,829 meters) deep. The world’s ocean canyons are much more impressive, but most people will never see them.
What is a sounding?
A sounding is a method once used for determining the depth of the ocean by dropping a weighted line into the water and measuring the length of that line when it stops descending at certain predetermined points.
Where is the farthest point from land?
In the middle of the South Pacific Ocean lies the Pacific pole of inaccessibility, a spot on the Earth that is the farthest from any land. It is 1,670 miles (2,688 km) from any land. Located at 48°52.6′ South and 123°23.6′ West, this spot is approximately equidistant from Antarctica, Australia, and Pitcairn Island.
Where is the farthest point from an ocean?
The Eurasian pole of inaccessibility is located in Xinjiang Province, in northern China, and is over 1,600 miles (2,574 km) from any ocean. Located at 46°17′ North, 86°40′ East, the land is approximately equidistant from the Arctic Ocean, Indian Ocean, and Pacific Ocean.
What is the world’s largest island?
The world’s largest island is Greenland (in Greenlandic, Kalaallit Nunaat). Greenland is located in the North Atlantic Ocean near Canada, between the latitudes of 59′ and 83′ North, and longitudes of 11′ and 74′ West. It is an autonomous country within the kingdom of Denmark, with the queen of Denmark as the head of state, but with a local referendum in 2008, it was granted self-rule and self-government. It is approximately 840,000 square miles (2,175,600 square km). Australia, while it also meets the usual definition of an island (surrounded by water) and is larger than Greenland, is not considered an island but a continent.
Why is Greenland considered an island while Australia is a continent?
Australia is three and a half times larger than Greenland and comprises most of the land on the Indo-Australian Plate, while Greenland is distinctly part of the North American Plate.
What is an archipelago?
An archipelago is a chain (or group) of islands that are close to one another. The Aleutian Islands of Alaska and the Hawaiian Islands are both archipelagos. They are usually formed by plates pushing into one another or by volcanic activity.
Atolls like these in the Maldives are formed of coral reefs surrounding what was once a volcano.
What is a coral reef?
Coral reefs are formed by the accumulation of calcium carbonate that comes from the external skeletons of tiny animals called coral polyps. The polyps live in shallow, warm water and thus congregate around islands in the tropics, where coral reefs are abundant.
What is an atoll?
In addition to reefs, coral can also form atolls. Atolls are formed when a volcano, around which coral often grows, erodes away, leaving a circular wall of coral with a lagoon at the center.
What is a strait?
A strait is a narrow body of water between islands or continents that connects two larger bodies of water. Two of the most famous straits are the Strait of Gibraltar, which connects the Mediterranean Sea and the Atlantic Ocean, and the Strait of Hormuz, which connects the Persian Gulf to the Gulf of Oman.
HIGH, LOW, BIG, SMALL, AND WONDROUS
Where is the lowest point on Earth?
To reach the lowest point on Earth, you would have to go far below the Pacific Ocean, south of Guam to the Marianas Trench, at a place known as Challenger Deep. Its maximum known depth is 6.831 miles or 36,070 feet (10,994 meters).
Is the lowest point on Earth actually closer to the center of the Earth?
No, because of the Earth’s irregular shape—it is not a perfect sphere—places in the Arctic Ocean are technically closer to the Earth’s center than the Mariana Trench, although not as deep.
Where is the world’s lowest point on dry land?
The world’s lowest point is at the shore of the Dead Sea on the border of Palestine, Israel, and Jordan. It is 1,378 feet (420 meters) below sea level.
What are the lowest points on each continent?
In Africa, the lowest point is Lake Assal in Djibouti, 509 feet (155 meters) below sea level. In North America, California’s Death Valley lies at 282 feet (86 meters) below sea level. Argentina’s Laguna del Carbón is the lowest point in South America at 345 feet (105 meters) below sea level. The Caspian Sea in Europe lies at 92 feet (28 meters) below sea level. In Asia the shoreline of the Dead Sea lies at 1,378 feet (420 meters) below sea level. And Australia’s lowest point is a mere 52 feet (16 meters) below sea level at Lake Eyre.
How does the hydrologic cycle work?
The movement of water from the atmosphere to the land, rivers, oceans, and plants and then back into the atmosphere is known as the hydrologic cycle. We can pick an arbitrary point in the cycle to begin our examination. Water in the atmosphere forms clouds or fog and falls (precipitates) to the ground. Water then flows into the ground to nourish plants or into streams that lead to rivers and then to oceans, or it can flow into the groundwater (underground sources of water). Over time, water sitting in puddles, rivers, and oceans evaporates into the atmosphere. Water in plants is transpired into the atmosphere.
What is evapotranspiration?
The process of water moving into the atmosphere is collectively known as evapotranspiration. It is the combination of water vapor being evaporated from the surface of the Earth (such as from lakes, rivers, or puddles) into the atmosphere, and transpiration, which is the movement of water from plants to the air.
Where is all the water?
Over 97% of the world’s water is contained within oceans and is too salty to drink or to irrigate crops with (except when the water is cleaned through a desalination plant, which is not done very often). About 2.8% of the world’s water supply is fresh water. Of that 2.8%, about 2% is frozen in glaciers and ice sheets. This leaves only about 0.8% of the world’s water that is accessible through aquifers, streams, lakes, and in the atmosphere. The water that we use primarily comes from this 0.8%.
How many people in the world have limited access to clean water?
According to experts at MIT, approximately 700 million people have limited access to clean water. This number will swell to approximately 1.8 billion people over the next ten years as the global population grows and demand for industrial water used for manufacturing, power generation, agriculture, and energy production continues to accelerate.
What is desalination?
Desalination is the process of removing some salt and minerals from ocean water in order to produce consumable fresh water for a population. According to experts at the International Desalination Association, there are approximately 17,000 desalination plants worldwide in 150 countries, producing 21.1 billion gallons (66.5 cubic meters) per day. Three hundred million people in the world rely on desalinated water for their daily drink water needs. Twenty percent of all water used in Israel is desalinated water that comes from the Mediterranean Sea. It is estimated that by 2016, 50% of Israel’s water supply will be produced in the country’s desalination plants.
Desalination plants remove salt from seawater to create fresh drinking water. The process has improved over the years, but there is still the problem of what to do with all the salt and other minerals that are generated from the process.
What is a desalination plant?
A desalination plant is a facility that pumps ordinary seawater through a myriad of expensive equipment and processes, transforming the salty water into fresh water. This process has been used with some success in many parts of the world, including the United States, the Caribbean, and the Middle East. It is much more efficient and less expensive, however, to clean wastewater (water that has been used for bathing, cooking, cleaning, etc.) than it is to clean and desalinate seawater.
How many desalination plants are there?
There are approximately 17,000 plants located throughout the world. Saudi Arabia alone accounts for 24% of the world output of fresh water from desalination. More than half of the world’s desalination plants are located in the Middle East due to the need for fresh water for the petroleum industry. The United States accounts for another 15% of all plants, Europe and Asia 10% each, and Africa approximately 6%.
Where is the biggest desalination plant in the United States?
The biggest desalination plant is in Carlsbad, California, where it opened in December 2015 at a cost of approximately $1 billion. It is capable of producing 50 million gallons (188 million liters) of drinking water to arid San Diego County per day. This is a fraction of the largest plant in the world, the Jebel Ali Plant in the United Arab Emirates, which produces over 140 million gallons (530 million liters) per day.
What is an aquifer?
An aquifer is an underground collection of water that is surrounded by rock. The creation of an aquifer is a very slow process, as it relies upon precipitated water (rainwater) to percolate through the soil and rock layers and into the aquifer. An aquifer lies above a lower layer of rock that holds the water in place and keeps it from moving further underground.
What is the Ogallala Aquifer?
The Ogallala Aquifer is a huge aquifer that spans an area from western Texas to South Dakota, including parts of Colorado, Kansas, Nebraska, Oklahoma, and New Mexico. The oldest water deposited in the aquifer is over one million years old, and only a very small amount of water is added each year. The Ogallala Aquifer is being pumped rapidly by the farms in the region, causing a reduction in the amount of water in the aquifer. Consequently, wells have to be continually deepened so that they can continue to pump water. The aquifer supports 20% of the wheat, corn, cotton, and cattle produced in the United States.
Why are we losing groundwater?
Water is pumped from aquifers around the world for irrigation, industrial, and household needs. Aquifers do not refill as rapidly as water is being pumped out, so in many areas, there is a danger that some aquifers may disappear altogether.
What are ice ages?
Ice ages began during the Precambrian Era approximately 600 million years ago. Throughout the life of the planet, the climate has warmed and cooled many times. During the cooling periods, ice ages have occurred. Large sheets of ice cover large portions of land. In the most recent ice age, which began approximately 3 million years ago and ended about 10,000 years ago, large parts of northern Europe and North America were covered by ice sheets. Some experts argue that there is evidence to suggest that the most recent ice age continues to this very day.
Will there be another ice age?
Yes, eventually the Earth will again cool and ice will cover land at higher latitudes and elevations. It may be a hundred years from now or it may be thousands of years away, but the Earth’s climate is always slowly changing.
If I keep walking in a straight line, will the Coriolis effect cause me to veer off in one direction or another?
If your body were completely symmetrical (it is not) and neither leg were longer and you were walking on perfectly flat land, then, yes, you might start veering due to the Coriolis effect.
What is the Coriolis effect?
Due to the rotation of the Earth, any object on or near the Earth’s surface will veer to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. This applies especially to phenomena such as ocean currents and wind. Imagine an airplane flying to New York from Los Angeles. As the plane flies over the United States, the Earth continues to rotate under the plane, and it lands in New Jersey instead. Pilots need to factor the spinning of the Earth into their trajectories in order to end up in the right place. North of the equator, ocean currents and winds rotate clockwise, but south of the equator, the opposite is true.
Does the Coriolis effect make the water in my toilet, sink, and bathtub swirl clockwise?
No, the Coriolis effect has very little effect on such small bodies of water. The flow down the drain is mostly a function of the shape of the container that holds the water.
What is the difference between a bay and a gulf?
Both a bay and a gulf are bodies of water partially surrounded by land, but a bay is a smaller version of a gulf. Famous bays include the San Francisco Bay (California), the Bay of Pigs (Cuba), Chesapeake Bay (Maryland/Virginia area), Hudson Bay (Canada), the Bay of Bengal (near India and Southeast Asia), and the Bay of Biscay (France). Famous gulfs include the Gulf of Mexico (southern United States), the Persian Gulf (between Saudi Arabia and Iran), and the Gulf of Aden (between the Red Sea and the Arabian Sea).
Where does the Loch Ness Monster live?
Loch Ness lies along a natural fault line in Scotland. The fabled monster is supposed to live in Loch Ness. The term “loch” is Gaelic and is used in Scotland to refer to a lake or narrow inlet of the sea. Loch Ness is fully surrounded by land and is therefore a lake. The first recorded sighting of this alleged monster was in the sixth century C.E. by St. Columba. In 1933, the first photograph of the supposed monster, known as Nessie, was taken.
How are waves created?
Waves are created by wind blowing across the surface of water. Though waves appear to move along the surface of the water, they are simply the movement (oscillation) of water up and down due to the friction of the air. When waves occur near the shore, they may become steeper and “break.”
How does the Old Faithful geyser shoot water into the air?
A geyser, such as the famous Old Faithful, located in Wyoming’s Yellowstone National Park, is the result of an underground aquifer that is warmed by heated rocks and magma. There is a small fissure or crack in this aquifer’s surface that allows the steam and heated water to jet from the ground (about every hour).
Possibly the most famous geyser on the planet is Old Faithful in Yellowstone National Park.
How does water wash away the land?
Drops of rain hit soil and rock and displace grains of material. When water flows over the surface, it loosens and carries away pieces of rock or soil. There is a tremendous amount of energy in a raindrop. Over days, weeks, months, years, centuries, and millennia, the erosive power of water can cut through even the strongest rocks. The material that the flowing water picks up is eventually deposited when the flow of the stream slows down, a process known as deposition.
How much does a gallon of water weigh?
Water is quite a heavy substance. One gallon of water at room temperature weighs about 8.33 pounds (3.78 kilograms).
How is water used in the home?
In the United States, we use approximately 80 to 100 gallons of water per day. A typical family of four people might use up to 400 gallons of water per day. About 26.7% of household water is used for flushing toilets; 21.7% is used for washing clothes; 20% may be used for washing dishes. The remaining water that we use is for showers/baths, drinking, and drips/leaks.
What waterfall has the largest flow of water?
Boyoma Falls (formerly known as Stanley Falls), on the Congo River in the central African nation of the Democratic Republic of the Congo, has the greatest flow of water in the world, estimated to be 4.49 million gallons per second (17 million liters per second), over the course of a drop of 196.85 feet (60 meters).
What is the most visited waterfall in the world?
Niagara Falls, on the border of Canada and the United States between Lake Ontario and Lake Erie, has 212,000 cubic feet (6,000 cubic meters) of water flowing over its 173- and 182-foot-high (52.7- and 55.5- meter-high) waterfalls.
What is the highest waterfall in the world?
The highest waterfall in the world is Angel Falls, located in Canaima National Park in southeast Venezuela. It is 3,212 feet (979 meters) high.
How does the boiling point of water help determine altitude?
The boiling point of water at sea level is 212 degrees Fahrenheit (100 degrees Celsius). The boiling point drops about one degree for every 500-foot (152-meter) increase in altitude. Therefore, in Denver, Colorado, in the United States, at 5,280 feet (1,609 meters) above sea level, water boils at about 202 degrees Fahrenheit (94.4 degrees Celsius). The change in the boiling point is why cooking instructions are nearly always modified for higher altitudes, when they involve the use of boiling water.
The spectacular Yosemite Falls in California’s Sierra Nevada Mountains is 2,425 feet (739 meters) high.
What is the difference between a sea and an ocean?
While a sea can be any body of saltwater, it usually refers to a body of saltwater partially or completely enclosed by land. Oceans, though they can also be referred to as seas, are large areas of saltwater, unobstructed by continents.
How salty is seawater?
About 3.5% of the weight of seawater is salt (not just sodium chloride or table salt, but also potassium chloride, calcium chloride, and other types of salts). This would equal just over three and one-third cups of salt in one gallon of seawater.
What are ocean currents?
The oceans don’t remain still; their water is constantly moving in giant circles known as currents. In the Northern Hemisphere, currents move clockwise, while in the Southern Hemisphere, they move counterclockwise. Currents help to moderate temperatures on land in such northern places as the British Isles, which are farther north than the United States/Canadian border, by sending warm water from the Caribbean northeast across the Atlantic Ocean to northern Europe. A current known as the Antarctic Circumpolar Current circles the southern continent. The North Atlantic and North Pacific oceans each have a large clockwise current, while the South Atlantic and South Pacific oceans each have a large counterclockwise current.
How tall is the tallest waterfall in the United States?
Yosemite Falls in California, which is comprised of three separate falls, has a height of 2,425 feet (739 meters).
What are the largest seas?
Parts of oceans that are surrounded by islands or otherwise partially enclosed are often known as seas. The five largest seas in order are: the South China Sea, the Caribbean Sea, the Mediterranean, the Bering Sea, and the Gulf of Mexico.
Why is the Mediterranean Sea so salty?
Due to the high temperatures in the Mediterranean region, evaporation of the Mediterranean Sea occurs more rapidly than in other bodies of water; therefore, more salt is left behind. The warm, dense, salty water in the Mediterranean is replaced by less salty and dense Atlantic water in the western part of the sea at the Strait of Gibraltar. Water that flows into the Mediterranean from the Atlantic Ocean usually remains in the sea for anywhere from 80 to 100 years before returning to the Atlantic Ocean.
Has the Mediterranean Sea always been there?
Salt and sediment found at the bottom of the Mediterranean Sea prove that on several occasions the Mediterranean Sea has dried up, leaving a large layer of salt behind. Scientists speculate that the Strait of Gibraltar has, on occasion, closed up, keeping water from being able to flow back and forth between the Atlantic Ocean and the Mediterranean Sea.
Where are the four colored seas: Black, Yellow, Red, and White?
The four colored seas are not geographically associated with one another. The Black Sea is located near the Balkan Peninsula and is bordered by Turkey, Russia, and Ukraine (it is also the home of the port city of Odessa). The Red Sea is located to the south of the Black Sea, between the Arabian Peninsula (Saudi Arabia) and Africa. The Red Sea has been a major trade route for hundreds of years and has been especially useful since the completion of the Suez Canal. The White Sea is in northern Europe. It is part of the Arctic Ocean and is a Russian sea (it lies to the east of Finland). The Yellow Sea is far to the east, between China and the Korean Peninsula.
What are the seven seas?
The “seven seas” spoken of by mariners from long ago are oceans or parts of oceans. The Atlantic and Pacific oceans are so large that they were each divided into two “seas.” The Antarctic, Indian, and Arctic were also considered seas, thus totaling seven. If a sailor had sailed upon all seven seas, he had sailed around the world. There are not just seven but dozens of seas in the world.
Is the Black Sea really black?
No, it is not. This sea, located to the north of Turkey, is quite deep and has darker-looking water than most water bodies, but receives its name from the severity of the waters when sailing.
Where is the Putrid Sea?
The Putrid Sea, also known as the Syvash Sea or Rotten Sea, lies to the east of the Isthmus of Perekop, between Crimea and Ukraine. It is a swampy area of salty lagoons that lie along the west coast of the Sea of Azov and cover an area of approximately 990 square miles (2,560 square km).
What is the longest river in the world?
Egypt’s famous Nile River is the longest in the world. It is more than 4,100 miles (6,597 km) long from its sources in the Ethiopian Highlands (the source of the portion of the Nile called the Blue Nile) and Lake Victoria (the source of the White Nile). The Nile Valley is the center of contemporary and ancient Egyptian civilization. Following the Nile in length are the Amazon (in Brazil), the Missouri-Mississippi (United States), the Chang or Yangtze (China), the Huang He or Yellow (China), and the Ob (Russia).
Do rivers always flow from north to south?
No, they do not! Rivers always flow from higher ground to lower ground. Though we are familiar with rivers like the Mississippi River in the United States, which flows from north to south, rivers always flow the way gravity takes them. There are many major rivers in Europe, Asia, and North America that flow from south to north, such as the Ob in Russia, the Nile in Africa, and the Mackenzie in Canada.
The Nile River meanders through much of the eastern part of Africa and is a source of water for seven countries.
Why are the Blue Nile and White Nile rivers both called Niles?
The Nile River begins as two separate tributaries—the White Nile and the Blue Nile. The White Nile begins its flow from Lake Victoria in Eastern Africa, and the Blue Nile originates in the Ethiopian Highlands. The Blue Nile and the White Nile converge in Khartoum, the capital of the Sudan, and form the Nile River, which continues on to the Mediterranean. It is approximately 4,258 miles (6,853 km) long.
Was the flooding of the Nile predictable before dams were built?
The summer floods of the Nile River were so predictable that the Egyptian calendar was based on their rise and fall. Flooding on the Nile occurred from late June until late October. The floods brought nutrients and sediments beneficial to the nearby agricultural lands, making farming productive throughout the remainder of the year. Measuring scales called “nilometers” were placed along the river and not only measured the river height but also served as calendars. When Egypt’s Aswan Dam was completed in 1970, flooding on the lower stretches of the Nile ceased, but it still occurs in parts of the Sudan.
What is the longest river in the United States?
The Missouri-Mississippi River is the longest in the United States, approximately 3,860 miles (6,211 km) in length.
Where are the highest rivers in the world?
The highest rivers are in Tibet, where there are two that stand out from all the rest: the Ating River at 20,013 feet (6,100 meters) and the Brahmaputra River at 19,751 feet (6,020 meters).
Why are the Missouri and Mississippi rivers lumped together?
Actually, the Missouri River was incorrectly named. The Missouri River is the main feeder river of what is now known as the Mississippi River. Usually, the main feeder bears the same name as the rest of the river. Therefore, the full length of the Mississippi River, including the Missouri River, is known as the Missouri-Mississippi River.
Which river carries the most water?
By far, Brazil’s Amazon River carries more water to the sea than any other river in the world. The discharge at the mouth of the river is about seven million cubic feet (170,000 cubic meters) per second, which is about four times the flow of the Congo in Africa, the river ranked second in terms of discharge. It would take the Amazon only about 28 days to fill up Lake Erie. The Yangtze, Brahmaputra, Ganges, Yenisey, and Mississippi are other rivers with very high discharges.
What is a delta?
A delta is a low-lying area where a river meets the sea. Often, the river divides into many tributary streams, forming a triangular-shaped area. The river deposits a large amount of sediment at its mouth, creating excellent soil for farming once the channel of the stream moves. One of the most famous deltas is where the Nile River meets the Mediterranean Sea. Other major deltas include the Mississippi River Delta in Louisiana, the Ganges River Delta in India, and the Yangtze Delta in China. The word delta comes from the Greek letter delta, referring to its triangular shape when written.
Where are some of the world’s largest freshwater marshes?
The Okavango Delta, in the southern African country of Botswana, forms a marsh that is 5,800 square miles (15,000 square km) in area. The Okavango River empties into the arid Kalahari Desert, forming the largest freshwater marsh in the world. The Everglades in Florida is another one of the world’s largest marshes, consisting of 2,185 square miles (5,659 square km). The water across this southern Florida marsh averages six inches (15 centimeters) in depth. The Everglades is an endangered ecosystem, threatened by excess drainage and the introduction of exotic plants.
What is a drainage basin?
The area that includes all of the tributaries for an individual stream or river is its drainage basin. For example, the drainage basin for the St. Lawrence River includes the area surrounding the Great Lakes. Rivers such as the Platte (which has its own drainage basin) flow into the Missouri, and the Missouri flows into the Mississippi. The combined area drained by the Platte, the Missouri, the Mississippi, and all other Mississippi River tributaries combined create the third-largest drainage basin in the world. The Amazon has the largest drainage basin of any river, while the Congo has the second largest.
What is a tributary?
Any stream that flows into another stream is a tributary. Most major rivers have hundreds of tributaries, which on a map look like branches of a tree. One classification system of rivers is based upon the number of tributaries a river has.
What is a watershed?
A watershed is the boundary between drainage basins. It is usually the crest of a mountain where water flows on either side into two different drainage basins.
What is a wadi?
Wadi is the Arabic word for a gully or other stream bed that is dry for most of the year. A wadi is a channel for streams that develop during the short rainy season. The channels of wadis were probably initially carved when the desert regions of today had more rainfall.
What is a meander?
Streams and rivers that have carved a flat floodplain commonly flow in curves known as meanders. These S-shaped curves vary by the size and flow of the river. The river flows faster on the outside curve of the meander and therefore continues to cut and create a larger curve.
What is an oxbow lake?
An oxbow lake is a crescent-shaped lake that is formed when the meander, or curve of a river, is cut off from the rest of the river during a flood, or when the curve of the meander becomes so large that the river begins flowing along a new path. The curve that remains becomes its own lake. These can commonly be seen along the Mississippi River system.
What is the world’s largest lake?
The Caspian Sea (which is really a lake) is the largest lake in the world. Until 11 million years ago, it was contiguous with the world ocean, so it is a saltwater lake. It is surrounded by Russia, Kazakhstan, Turkmenistan, Iran, and Azerbaijan and is over 143,200 square miles (370,888 square km) in area. The second-largest lake in the world, Lake Superior in North America, is a mere 31,820 square miles (82,414 square km) in area and has more water than the other four neighboring Great Lakes combined. It is considered by many to be the largest freshwater lake in the world by surface area.
What is Africa’s largest lake?
Located in eastern Africa, Lake Victoria is Africa’s largest lake by area, with a surface area of approximately 26,828 square miles (69,485 square km). It is also the world’s second-largest freshwater lake, after Lake Superior. Lake Victoria is bordered by Uganda, Kenya, and Tanzania. The lake was named by British explorer John Hanning Speke, the first European to see the lake (in 1858), in honor of the reigning British queen. A map, drawn by Arab explorers in the late twelfth century C.E., describes the lake in great detail.
The Caspian Sea is actually a very large lake located in southern Russia, which also touches Turkmenistan and Kazakhstan.
Where is the highest lake in the world?
A yet-to-be-named small crater lake found atop Ojos del Salado (Spanish for “eyes of salty water”), a volcanic mountain on the border of Argentina and Chile, has an elevation of 20,965 feet (6,390 meters). Lake Titicaca, a lake sandwiched between Peru and Bolivia, is at 12,507 feet (3,812 meters) above sea level and is the highest navigable lake in the world, which means that you can go for a boat ride on this lake.
How do we know how much rain actually falls?
Agencies like the National Weather Service use very accurate devices that measure rainfall to the nearest one-hundredth of an inch. The devices, known as rain gauges or tipping-bucket gauges, collect rainwater, usually at a point unaffected by local buildings or trees that may interfere with the rain.
Where in the world does it rain the most each year?
Cherrapunji and the nearby town of Mawsynram, in India, near the border of Bangladesh, have the highest average rainfall per year in the world, averaging 467 inches (11,872 mm). They are in a subtropical climate zone and are impacted by monsoon rains that are heavy during the months of April through October. Mt. Waialeale, on the island of Kauai in Hawaii, receives an average of 452 inches (11,500 mm) of rain a year and often records some of the highest average precipitation in the world.
Where does it rain the least?
The Dry Valleys of Antarctica are considered to be among the driest places on Earth, with annual precipitation of less than .08 inches (2 mm). Because of its proximity to the Atacama Desert, Arica, Chile, is also considered by many to be one of the world’s driest places with an average annual rainfall of .03 inches (.761 mm). The northern Sudan’s Wadi Halfa (which is in the Sahara Desert) receives an average of less than .10 inches (2.54 mm) of rain per year. That’s hardly a drop at the bottom of a bucket.
How much water is in snow?
When about 10 inches (25 centimeters) of snow melts, it turns into about one inch (2.54 cm) of water. Snow has pockets of air between snowflakes when they are on the ground, so it takes ten times the amount of snow to make an equivalent amount of water.
How can I measure the amount of rain that falls where I live?
Any container with a flat bottom and flat sides can measure rainfall. The width of the top of the container must be the same as at the bottom of the container, but the diameter does not matter. It could be a device purchased for measuring precipitation or something as simple as a coffee can.
Do oceans get more rain than land?
The oceans receive about 77 percent of the world’s precipitation. The remaining 23 percent of precipitation falls on the continents. Some areas of the world receive far more precipitation than others. Some parts of equatorial South America, Africa, Southeast Asia, and nearby islands receive over 200 inches (500 centimeters) of rain a year, while some desert areas receive only a fraction of an inch of rain per year.
Where was the most snowfall ever recorded?
Washington State’s Mt. Baker, at an elevation of 4,200 feet (1,280 meters), recorded the most snowfall in a single season (July 1998–June 1999): 1,140 inches (2,896 centimeters), which is 95 feet (28.96 meters) of snow.
What is the difference between snow and hail?
Snow is water vapor that freezes in clouds before falling to the Earth. Hail is water droplets (raindrops) that have turned to ice inside of clouds.
How is hail formed?
Hail is ice that is formed in large thunderstorm clouds. Hail begins as droplets of water, normally destined to become raindrops, that are blown upward and subsequently freeze. They then fall lower within the cloud, where they collect more water, are blown upward again, and refreeze. The hailstone grows larger as it collects more and more ice and eventually falls to the ground.
How big was the largest hailstone?
In 2010, a hailstone that fell near Vivian, South Dakota, measured 8 inches (20.32 cm) in diameter with a circumference of 18.62 inches (47.3 cm), even after six hours of thawing. It weighed 1 pound, 15 ounces (878.84 grams). In 2003, a hailstone was recovered near Aurora, Nebraska, with a diameter of 18.75 inches (47.63 centimeters). The previous record was in 1970, when people recovered a hailstone with a 17.5 inches (44.45 centimeters) diameter in Kansas.
What is a glacier?
A glacier is a mass of ice that stays frozen throughout the year and flows downhill. Glaciers are capable of carving rock with their weight and slow, steady movement. They are responsible for the stunning landscape of Yosemite National Park in California. Large glaciers that cover the land are also known as ice sheets.
Are there still glaciers in the United States?
Yes, small glaciers exist throughout Alaska, within the Cascade Range of Washington State, sporadically across the Rocky Mountains, and also in the Sierra Nevada Mountains of California.
How old are glaciers?
Glaciers present today were created during the last stage of glaciation, the Pleistocene epoch, which lasted from 1.6 million years ago to about 10,000 years ago.
Glaciers around the world, including Serrano Glacier in O’Higgins National Park, Chile, have been receding due to global warming.
Did glaciers create the Great Lakes?
Yes, the Great Lakes are the world’s largest lakes formed by glaciers. During the Pleistocene epoch, glaciers inched over the Great Lakes area, moving weak rock out of their way and leaving behind huge, carved basins. As the glaciers began to melt, the basins filled with water and created the Great Lakes.
Are glaciers only found in cold, northern places?
No, glaciers are found in all six continents.
What is a tropical glacier?
Tropical glaciers are those found high in the mountains of tropical regions in the world. The Andes Mountains in South America contain 70% of the world’s tropical glaciers.
Is global warming causing the world’s glaciers to melt?
Many scientists believe that greenhouse gases from human activities, and the effect of this on global temperatures, are directly causing glaciers in all parts of the world to melt and recede at an unprecedented rate. It is thought that by 2030, there will be no glaciers in Glacier National Park in Montana. In East Africa, Mt. Kenya’s Lewis Glacier in Kenya has lost 40% of its size in just the last twenty-five years.
What are the consequences when glaciers melt?
Glaciers that have melted in the Himalayas, home to the world’s largest mountains, have filled up and burst the banks of nearby glacial lakes, filling rivers and causing widespread flooding and death to nearby populations downstream. Similar consequences will likely befall those now living near other glaciers around the world.
From where does the word “fjord” originate?
The word fjord comes from the Norse language and means “where you travel across.” It is significant to early Norwegians as a place to travel across to get to the sea when there were no bridges available.
What is a fjord?
During the ice ages, glaciers, which were prevalent at higher latitudes and elevations, became so large that gravity drove them to lower elevations, eventually all the way to the sea. On their way, glaciers would carve deep canyons in the surface of the Earth. At the end of the ice age, as the ice melted and the ocean level rose, these glacial troughs filled with seawater. These very dramatic-looking canyons with high cliffs hanging over a thin bay of water are known as fjords. Fjords are very common in Norway and Alaska.
What is the highest fjord in Norway?
The highest fjord is Sognefjord, which begins at a depth of 4,291 feet (1,308 meters) in the ocean and rises to more than 3,280 feet (1,000 meters).
Are all fjords found in Norway?
No. In fact, fjords are found throughout the world, wherever glaciers retreated and have cut into the earth, filling in and creating a huge valley of seawater. Notable fjords are found in Alaska and on New Zealand’s South Island.
Where is the longest fjord?
The longest fjord is in Greenland, at Scoresby Sund. It stretches more than 217 miles (350 km). English explorer William Scoresby mapped the fjord in 1822.
What is a dam?
By blocking the flow of a river, a dam allows a reservoir of water to build up. Dams are built in order to minimize floods, to provide water for agriculture, and to provide water for recreational uses. Dams in the United States are somewhat controversial, as the U.S. Bureau of Reclamation (established in 1902) and the Army’s Corps of Engineers battle to build more dams and control more water in the western United States. Many outdoor enthusiasts and environmentalists feel that dams are not always necessary.
What is the tallest dam in the world?
China is home to three of the top four highest dams in the world. The highest in the world, the Jinping-I Dam on the Yalong River in Sichuan Province in China, is 1,001 feet (305 meters) high. Tajikistan is home to the second-highest dam in the world, the Nurek, which stands 980 feet (380 meters) high. The United States’ tallest dam, Oroville Dam (in Northern California), is currently ranked twenty-fourth on the world list at 750 feet (228.6 meters) high.
How do farmers water their crops?
The process of artificially watering crops is called irrigation. In some areas of the world, agriculture can rely on rainfall for all of its water needs. In drier areas, usually those receiving less than 20 inches (51 centimeters) of rainfall per year, irrigation is required. Water is pumped from aquifers or delivered via an aqueduct to the fields, where it flows through small channels between plants or is sprayed through sprinklers. In very water-conservative regions such as Israel, water is scientifically dripped onto plants, thereby providing the exact amount of water necessary.
Although they were constructed many centuries ago, Roman aqueducts such as Pont del Diable in Tarragona, Spain, still stand today, a legacy of amazing engineering from ancient times.
How did the ancient Romans and Mesopotamians get water to their cities?
The ancient Romans and Mesopotamians built aqueducts to transport water between a source and areas where it was needed for agriculture or civilization. The Roman system was very extensive and was constructed throughout its empire. Some portions of these ancient aqueducts are still in use. Today, modern, concrete-lined channels transport water hundreds of miles. The most extensive aqueduct systems in the world today are those that bring water to southern California from the Colorado River in the east and from the Sacramento River in the north.
Were the Romans the only civilization to develop water resources in an advanced way?
No, recent excavations in Henan Province in China uncovered a network of clay pipes built during the Eastern Zhou Dynasty (1122 to 256 B.C.E.). The pipes were connected to many reservoirs around the cities, using technology that may actually predate Roman water works.
Where is the biggest hydroelectric dam in the world?
The Three Gorges Dam, which spans the Yangtze River in China’s Hubei Province, is the biggest hydroelectric dam in the world. Completed in 2012, it generates more power than any power station in the world, producing 98.8 terawatt hours of power. It is capable of generating 22,500 megawatts of power using 32 turbines. Over 1,300,000 people were displaced as result of living in the valleys above the site of the dam. This fact, along with the potential loss of thousands of archaeological sites, has been a source of controversy since the project was conceived in the 1990s.
