On this day in 1781, General George Washington, commanding a force of 17,000 French and Continental troops, begins the siege known as the Battle of Yorktown against British General Lord Charles Cornwallis and a contingent of 9,000 British troops at Yorktown, Virginia, in the most important battle of the Revolutionary War.
Earth's rotation causes the trade winds, in a way. If Earth didn't rotate, the wind at these latitudes would blow straight from the subtropical highs to the ITCZ.n the Northern Hemisphere, the Earth rotates counterclockwise so the wind is deflected to the right. The Southern Hemisphere rotates clockwise deflecting the wind to the left. Regardless, the Coriolis effect only influences the direction of the wind, not its speed.
Trade Winds. In the Northern Hemisphere, warm air around the equator rises and flows north toward the pole. As the air moves away from the equator, the Coriolis effect deflects it toward the right. It cools and descends near 30 degrees North latitude. The descending air blows from the northeast to the southwest, back toward the equator (Ross, 1995). A similar wind pattern occurs in the Southern Hemisphere; these winds blow from the southeast toward the northwest and descend near 30 degrees South latitude. These prevailing winds, known as the trade winds, meet at the Intertropical Convergence Zone (also called the doldrums) between 5 degrees North and 5 degrees South latitude, where the winds are calm. The remaining air (air that does not descend at 30 degrees North or South latitude) continues toward the poles and is known as the westerly winds, or westerlies. The trade winds are so named because ships have historically taken advantage of them to aid their journies between Europe and the Americas (Bowditch, 1995).