Investigating Wind Systems in the Real World

• Click here to see a full global view (i.e. Mercator projection) showing the air circulation patterns over the Earth for May 5, 2012.

1. How does this view compare to the idealized three-cell model?
There are definite curves in the wind pattern (i.e. the Coriolis effect), but the overall pattern definitely appears much more chaotic and certainly lacks the uniformity of the three-cell model.

The view to the right represents data for only one day. One day, however, is very short-term. Atmospheric conditions and air pressure systems may be too variable to notice a pattern on such a short time scale. Patterns should, however, become more obvious if we examine long-term (i.e. monthly) air circulation data.

• Click here to view air pressure systems for January 2008.
• Click here to add in corresponding wind circulation patterns as a result of the air pressure systems.
• Rotate the globe and examine the wind circulation systems. Note in particular the relationship between pressure systems and the accompanying wind patterns.
• Click here for a Mercator projection in order to see a full global view of the wind systems. (Note: Isobars have been replaced by colored pressure gradients for clarity in seeing the overall picture on wind systems.)

2. What parts of this full global view seem to have some correspondence to the three-cell model? (Click here if you need to see the three-cell model again.)
There are definite patterns visible in the monthly global view. Areas in the Atlantic and Pacific oceans both north and south of the equator show nice circular patterns that appear to correspond to the Trade Winds and the Westerlies. Polar Easterlies also appear to be visible in the Arctic and Antarctic areas. Water areas appear to have some correspondence to the three-cell model.

• Click here to zoom in on the North Atlantic.
• Examine this view carefully and attempt to locate the Trade Winds, the Westerlies, and the Polar Easterlies.
• Click here for an annotated view of the wind systems in order to check your answers.
• Try this again by clicking here to zoom in on the North Pacific. Again attempt to locate the Trade Winds, the Westerlies, and the Polar Easterlies.
• Click here for an annotated view in order to check your answers.
• Click here to return to the full global view (i.e. Mercator projection).

3. What geographic areas do not seem to correspond particularly well to the three-cell model?
Landmass areas do not appear to correspond particularly well to patterns in the three-cell model. Air pressure and wind circulation appears to be quite different, even chaotic, over landmass areas, particularly when compared to ocean areas.


4. Why do you think landmasses appear to break up the air circulation patterns?
Land surface areas have quite a varied topography. This will certainly serve to disturb air pressure and wind circulation systems, particularly when compared to the flat, uniform ocean surface. Large landmasses also go through large seasonal differences in temperature because of the tilt in the Earth’s axis of rotation. This results in large seasonal changes in air pressure systems over land areas.

Topography and seasonal temperature difference are two reasons why wind circulation systems over continents can differ quite markedly from the three-cell model.

• Click here to see a view of the Earth’s landmasses.

5. Which hemisphere contains more landmass, and which hemisphere contains more water?
The northern hemisphere contains more landmass, while the southern hemisphere contains more water. (The northern hemisphere is approximately 40% land and 60% water, while the southern hemisphere is approximately 20% land and 80% water.)


6. In which hemisphere would the air pressure and wind circulation systems over the course of the year (i.e. comparing January and July conditions):
   
   
   1. remain the most stable? Why?
   Air pressure and wind circulation systems should generally remain the most stable in the southern hemisphere because of the large expanse of water present there. The temperature of the water changes very little over the course of the year. This coupled with the flat surface nature of the ocean should lead to great stability in wind and air pressure systems.
   
   
   2. change the most? Why?
   The wind and air pressure systems in the northern hemisphere, on the other hand, should be quite variable over the course of the year. Differences in seasonal heating of the large landmasses in the northern hemisphere should be a major factor in this variable behavior.

• Click here to see the air pressure and wind systems for July 2008. (Click here if you need to return to the January 2008 data for comparison.)

7. Was your answer to question 6 correct? Explain.
Yes, my answer to question 6 was correct. Air circulation systems in the southern hemisphere were fairly stable because of the large amount of water present. The air circulation systems in the northern hemisphere varied quite a bit over the continents, primarily because of seasonal heating.