WEATHER

WEATHER

Combine the heat of the sun with the rotation atmosphere. The differences in tem of a planet covered mostly in water, and the perature and pressure that cause such profound day-to-day shifts at product is what we call weather: the day-to- ground level smooth out higher in day changes in the quality of the atmosphere the atmosphere, where the air is cold and "thin." a term referring to lower oxygen levels. The highest jet stream air currents, which roar around the globe 6 to 9 miles above its surface at speeds of up to 250 miles per hour.

near the surface of the Earth. Fundamentally, weather is caused by the sun, which heats the air at the winds that shape weather are the planet's bulging equatorial regions more than at either Pole.

Because hotter air rises and cooler air falls, the difference in temperature across the planet causes masses of air to begin to move. We feel that moving air as wind. The movement of the air becomes even more dynamic because of Earth's rotation, while the steady evaporation of surface water leads to

the formation of clouds, and eventually precipitation.

Weather is the result of a global system of moving air and moisture, but it can also be shaped by local features such as mountain ranges or nearby bodies of water. Weather occurs only in the lower

FAST FACT Lightning can reach temperatures of around 54,000°F.

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The effects of humidity-another word for the saturation of air with evaporated water can be felt at warmer temperatures, Cooler air has a lower saturation point than warmer air. As warm, water-soaked air mole cules rise, they also cool. Their saturation point drops.