Читать книгу Weather For Dummies - John D. Cox - Страница 65

You and I are part and parcel of Earth’s motions in space, and the planet’s atmosphere also is going along for the ride. Although Earthlings are traveling in a yearlong revolution around the Sun, speeding through space, they have no sensation of this movement. Thank goodness for that! Talk about being blown away!

Also, people have no sensation of dizziness even though the planet is spinning like a top in a rate of rotation that completes itself every 24 hours. A person standing at the Equator not only is traveling through space along with the planet, but at the same time is spinning with the planet at more than 1,000 miles per hour. It’s like a whirligig carnival ride, revolving on one level and spinning on another, and I’m getting a little queasy just thinking about it.

The rotation or spin of Earth has a big impact on daily weather. Every moment, 24 hours a day, a new patch of the Earth is being exposed to the warming rays of the Sun after the cooling effects of darkness. Exactly around the world, a patch in daylight is becoming shrouded in the shade of the spinning planet. This constant routine is sending radiant heating and cooling through the atmosphere like a wave.

Such is the fickle pace of many daily weather events. The hot summer afternoon can conspire with the moist air to produce a violent local storm of lightning and thunder and hail. The ground and the town below it can be left in a mess in an hour or two, and before long, the sky can show not the slightest sign of what happened.

Earth’s rotation is responsible for some very large and powerful weather-related motions in the atmosphere. For example, weather patterns in the middle latitudes move from west to east because of Earth’s spin. It is responsible for the west-to-east direction of the powerful polar jet streams and for the prevailing global winds, such as the tradewinds and the mid-latitude westerlies, which Chapter 5 describes in detail.