The Weather Systems
If earth were either all land or all water and did not rotate on its axis, a large convection cell would form in each hemisphere with the colder and denser air at the poles sinking to the surface and flowing toward the tropics. There, it would force the warm air already at the equator to rise, and then it would cool and flow back toward the poles. The problem with this proposal is that Earth does rotate from west to east. This rotation causes the Coriolis effect, wherein moving particles such as air are deflected to the right in the northern hemisphere and to the left in the southern hemisphere. The Coriolis effect, combines with the heat imbalance founded on Earth to create distinct global wind systems that transport colder air to warmer areas and warmer air to colder areas. The end result is the balancing of heat energy on Earth. Jet Streams: Earth’s weather is strongly influenced by atmospheric conditioned and events that occur at the boundaries between wind zones. On either side of these imaginary boundaries, both surface and upper-level air differs greatly in temperature and pressure. Remember that wind, temperature, and pressure are related. Differences in temperature and pressure cause wind. Therefore, a large temperature gradient in upper-level air should result in strong westerly winds, and indeed, this is what happens. Narrow bonds of fast, high-altitude, westerly winds called jet streams flow at a speed up to 185 km/h at elevations of 10.7 km to 12.2 km. Jet streams, are named because they resemble jets of water. The most significant one, the polar jet stream, separates the polar easterlies from the prevailing westerlies. A second version, the subtropical jet stream, is located where the trade winds meet the prevailing westerlies. Large-Scale Weather Systems: Disturbances from along jet streams and give rise to large-scale weather systems that transport at the position surface cold air toward the tropics and surface war air toward the poles. Keep