The strength and position of the Intertropical Convergence Zone influences tropical and global weather patterns. Air temperature differences across the Earth's surface both land and water create winds, with warm air being lighter than cold air. Near the equator, the sun heats the sea surface, causing the warm air at the surface to rise and be replaced by the trade winds blowing from subtropical high pressure systems into equatorial low-pressure troughs.
The trade winds blow steadily for days and are among the most consistent on earth. When trade winds move over warm tropical waters, they pick up moisture and bring heavy rainfall to the windward-facing slopes of mountainous areas, contrasting with the downward motion of dry air that creates desert areas on land.
Because the area of Earth between the Tropic of Cancer and Tropic of Capricorn , lying at approximately 23 degrees latitude on either side of the equator, receives more solar heat than the rest of the earth, the warm air creates clouds and rain with thunder-showers there almost every day. The differences in pressure and temperature between the two sides of the Pacific are caused by the trade winds; air blowing from east to west pushes water, making the sea level higher in the western Pacific, and makes cold water rise toward the surface, making the eastern Pacific approximately 14 degrees F 7.
The warm surface temperature is associated with reversed air pressure patterns and decreasing strength of trade winds, so more water stays in the eastern Pacific off the coast of South America.
With the rain pattern shift eastward, the western Pacific can become drier over India and much of southeast Asia. A similar pattern sets up in the Atlantic, resulting in extreme drought in the eastern United States and reduced tropical storm development in the Atlantic Ocean. The cooler surface temperature is associated with a rain pattern shift westward. Wind travels from areas of high pressure to areas of low pressure.
Additionally, heat and pressure cause the wind to shift direction. For example, a sea breeze forms when the land heats more rapidly than the water and the heated air rises and travels from the higher-pressure water inland.
A land breeze occurs when the opposite happens and the water retains more heat than the land. Additional factors that affect wind direction are the Coriolis Effect and Topography. Coriolis effect is the rotation of the earth from west to east, which, generally speaking, causes winds to blow in a counterclockwise or clockwise manner.
Tracking wind direction is hardly a new concept. In fact, the first weathervane was invented in 48 BC by Greek astronomer Andronicus.
But this extra precipitation is not spread evenly around the globe, and some places might actually get less precipitation than they used to get. That's because climate change causes shifts in air and ocean currents, which can change weather patterns. The amount of precipitation has changed in various parts of the United States since the early 20th century. On average, the world is already getting more precipitation now than it did years ago: 6 percent more in the United States and nearly 2 percent more worldwide.
The effects vary by region, though.
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