Global Wind Patterns Name ____________________________________
The Earth's surface is constantly being heated by energy from the sun. Because tropical regions are warmed more effectively than polar regions, differences in atmospheric pressure develop between these latitude extremes. Such pressure differences result in planet wide winds.
Air heated at the surface in the lower latitudes is lifted and replaced by cooler, denser air flowing from the higher latitudes. If the Earth did not rotate, if it were not inclined on its axis, and if the surface were uniform throughout, planetary atmospheric circulation would probably be relatively simple. Alas, such is not the case! In fact, global wind systems are extremely complex and details of worldwide wind patterns are still not clearly understood by scientists. However, basic circulation patterns do exist that is recognized by scientists and are used to help understand certain worldwide climate and weather patterns.
The purpose of this activity is to examine the location and extent of some of the general planetary wind and pressure systems that are currently recognized. In order to complete this activity, you will need to keep three facts in mind:
A. Air tends to flow out of regions characterized by relative high pressure and into regions characterized by relative low pressure.
B. Because of the Earth's rotation, winds tend to be deflected or directed toward the right in the northern hemisphere, and toward the left in the southern hemisphere.
C. Winds are named for the direction from which they originate. For example, a northerly wind is one that flows from the north.
Now refer to Figure 1 which represents a rough sketch of the Earth. Note that the locations of the equator (latitude zero), the poles (latitude 90°), and latitudes 30° and 60° have been identified. Additional information will be added to the map as you complete this activity.
On the right side of Figure 1 and
in the appropriate space provided, label each of the seven pressure belts. The
equator is a low pressure belt and is referred to as the Equatorial Low.
Latitudes 30° north and south are high pressure zones and are each referred to
as a Subtropical High. Latitudes 60° north and south are low pressure belts and
are each known as a Subpolar Low. Finally, the
In the proper location, sketch in the direction of planetary wind movement within each global wind belt. Use several arrows in each zone to illustrate the direction of deflection, as shown in the following key. Be sure to place directional arrows, right on the map, within all six wind belt regions.
On the left side of Figure 1 and in the appropriate space provided, label the names of the wind belts. Remember winds are named for the direction from which they flow. Winds located between latitudes zero and 30° are known as Trade winds. Thus, if winds within this zone originated in the northeast, they would be known as Northeast Trades. Winds located between latitudes 30° and 60° are referred to and named by the direction from which they have originated. They are further described as prevailing winds. Thus, if winds within these zones originated in the northwest, they would be referred to as Prevailing Northwesterlies. Winds located between latitudes 60° and 90° (the North or South poles) are referred to as Polar winds. Therefore, winds located in these zones, which originate in the east, are known as Polar Easterlies.
1. What causes winds to be deflected to the right or left as they flow from high pressure to low pressure?
2. Name the wind belt in which you live.
3. Name the prevailing winds that would be found at location X (refer to Figure 1).
Why is air pressure generally lower over equatorial regions than over