Define the term: WINDSWind is air in motion. It is produced by the uneven heating of the earths surface by the sun. Since the earths surface is made of various land and water formations, it absorbs the suns radiation unevenly. Two factors are necessary to specify wind: speed and direction. Winds are named for the direction from which they begin, not the direction they flow (example: A northerly wind blows air from north to south. A south westerly wind blows air from the southwest to the northeast.)There are two types:1. Local - Caused by changing air masses2. Global - Caused by the earth's rotation (Coriolis Effect) and movement of warm air away from the equator.

What are the global wind patterns?The equator receives the Sun's direct rays. Here, air is heated and rises, leaving low pressure areas behind. When air hits the equator, it heats up and rises, eventually being pulled down to the poles, where it becomes chilled, sinking close to the surface of the ocean and then being pushed back toward the equator by the pressure of cooling air from above. This creates a continuous cycle of air which moves slowly towards the equator near the surface of the Earth, with the air above moving toward the poles.

WHAT ARE TRADE WINDS? They are also called Tropical Westerlies. The trade winds are a consistent weather pattern of easterly winds which blow near the Earth's equator. They are warm, steady breezes that blow almost continuously. The Coriolis Effect makes the trade winds appear to be curving to the west, whether they are travelling to the equator from the south or north. The term trade in this case refers to a track or path, rather than commerce. Historical mariners found the trade winds of interest both because they could be used to speed sailing to the west.

They are surrounded by two other interesting wind patterns: the doldrums and the horse latitudes.What are the doldrums?It is also called the Inter-tropical Convergence Zone (ITCZ). The doldrums is an area of calm weather located at the equator. The trade winds coming from the south and the north meet near the equator. These converging trade winds produce general upward winds as they are heated, so there are no steady surface winds. In the horse latitudes above and below the equator, there are also periods of minimal wind which can cause ships to become stranded.

ADVANTAGES OF TRADE WINDS 1. Historically, finding the trade winds and sticking with them was extremely important, because ships could be stuck for extended periods of time in the doldrums or the horse latitudes, eventually running out of supplies.2. The trade winds also play an important role in global weather, bringing storms to the western coasts of Asia, Africa, and the Americas.

Although the trade winds are no longer of critical importance to merchant ships, since they do not rely on wind power, sailors continue to utilize the trade winds as a sort of oceanic fast lane to cut down on travel times across the Pacific and Atlantic.

(PREVAILING) WESTERLIESWhat are Westerlies? Winds which blow from the west towards the east located above the subtropical highs in the Northern Hemisphere, and below the subtropical highs in the Southern Hemisphere are called westerly winds, after the direction from whence the winds come. Prevailing westerlies in the Northern Hemisphere are responsible for many of the weather movements across the United States and Canada. Located between thirty and sixty degrees latitude, are the winds that move toward the poles appear to curve to the east. At the core of the westerly winds lies what scientists call a jet stream. Jet streams are super high-speed winds. Each hemispheres westerly has two main jet streams. Closer to the poles we find the polar jet stream. At slightly lower latitudes we find the subtropical jet stream.

Prevailing WindsWhat are prevailing winds? The prevailing wind is the wind that blows most frequently across a particular region. Different regions on Earth have different prevailing wind directions which are dependent upon the nature of the general circulation of the atmosphere and the latitudinal wind zones. CategoriesOn the global scale, prevailing winds are divided into three main categories: The northeast and southeast trade winds The westerlies The polar easterlies.Their varying locations and directions come from how the earth rotates and how the sun heats the atmosphere. For example, the sun's rays hit the equator most directly and thus, steadily heat the atmosphere there, which leads to a continuous rise of warm air around the equator.

MovementThe rising air at the equator gradually drifts north and south, where it eventually cools, sinks and, because of the convection effect, travels back to the equator. This continuous circulation of air -- the trade winds -- was used by ancient sailors to sail from Europe to the Americas since the trade winds blow from east to west. The prevailing westerly winds, because they're warmer than polar air, are drawn to the poles. Conversely, the colder, polar easterly winds seek warmer atmosphere and blow away from the poles. This basic pattern of heating and cooling and the convection effect from the earth's dominant winds.

Read more: What Are Dominant Winds? | eHow.com http://www.ehow.com/info_12021795_dominant-winds.html#ixzz2JbTV8YrD

Coriolis Effect- The earth's rotation causes air to move in a circular motion. The rotation of the Earth causes an interesting phenomenon on free moving objects on the Earth. Objects in the Northern Hemisphere are deflected to the right, while objects in the Southern Hemisphere are deflected to the left. When air meets at the equator, it is deflected due to a phenomenon called the Coriolis effect, which is caused by the rotation of the Earth. The deflection causes the winds to divert to the West, creating a steady flow of wind which is termed easterly because winds are named for the direction from which they originated, rather than the direction in which they are headed. The coriolis Effect and pressure gradient work against each other. Pressure gradient pushes winds outward, while the Coriolis Effect moves winds to the right or left. Often these two forces reach a balance, causing winds to blow sideways along the pressure gradient, not getting any further out from a high pressure or closer to a high pressure. This type of wind is known as a geostrophic wind.

Ferrels deflection Law Ferrel's law, named after American meteorologist W. Ferrel (1817-1891), is the rule that air or water moving horizontally in the Northern Hemisphere is deflected or pushed to the right of its line of motion while air or water moving horizontally in the Southern Hemisphere is deflected to the left of its line of motion. Ferrel's law applies equally to air and ocean movements, so the oceans circulate in the same sense as the air in both hemispheres. Ferrel's law is the change in direction of prevaling winds when it comes to the equator. This deflection is caused by some random molecular motion due to the rise in temperature. Ferrel's law predicts the directions of the large-scale circulations of the earth's atmosphere and oceans, is a restatement in global terms of the action of the Coriolis force.