At night, the opposite cycle occurs. Since the land cools quicker than water, air over the warmer water rises and flows toward cooler land where the air sinks. This reverse cycle of wind blowing out to sea is called a land breeze. On a global scale, the tropical regions receives more solar radiation and heatng than the poles. Similar to the sea and land breezes, the difference of heating of the earth s surface creates cycles of air movement.
Air moving between the two regions is curved by the rotation of the earth to create our wind.
The prevailing westerlies is the wnd belt across the United States generally moving weather systems from west to east. The same difference of the earth's heating that causes the prevailing westerlies also causes a strong tube of wind high above the surface of the earth. The Jet Stream is a narrow band of strong wind in the upper atmosphere. The jet stream is stronger in winter, since the temperature difference between the poles and the equator is gratest in the winter. During the winter, the jet stream is often the boundary separating cold polar air to the north from the warm subtropical air to the south.