Earth's Meteorological Monsters

Part B: Patterns of Hurricane Movement

Hurricanes move in generally predictable patterns. This part of the investigation focuses on these patterns for hurricanes in the Atlantic Ocean. First you'll examine the movie again to see if you can identify the patterns empirically. Then you will try to tie your observations together with information about global wind patterns.

Global Wind Pattern Effects

3-D Hadley Cell Diagram

This illustration from NASA describes the patterns of wind movement on the global scale. The sun heats the air over the equator more than at the poles. This differential heating causes warmer, less dense air near the equator to rise, and cells of convection develop. These are called Hadley cells. At the surface, the cells generate winds. On the image, the large arrows show the directions of surface wind flow in the different zones. Red and blue indicate the relative temperatures of the winds. You can see that global winds point towards the equator in the tropics and towards the poles between 30 and 60 degrees latitude. Use your mental visualization skills to imagine how these surface winds would look on a flat map of the world.

In this image, the tracks of all tropical cyclones between 1985 and 2005 have been overlayed on an image of Earth. Even with only 20 years of data, you can see the patterns of how hurricanes move across the world's oceans. The track lines in the image are made up of dots representing the position of each hurricane at 6 hour intervals. Each dot is color coded to correspond to the strength of the storm on the Saffir-Simpson Scale, as shown in the legend in the bottom right corner of the image. Consider how the data shown in this and the image above are related.

Stop and Think

3: Based on these two images, is there a connection between global wind patterns and the movement patterns of hurricanes? In your own words, describe how global wind patterns illustrated in the first image influence the overall patterns you see in the second image.
4: There are a few areas on the second image where there is little to no hurricane activity. The most prominent one of these is the empty stripe running along the equator. In the 20 years covered by this data, not a single hurricane has been seen to cross through this region from one hemisphere to the other. Based on what you've learned so far, hypothesize as to why we might expect this to be the case.
5: Does the absence of equator crossing storms in the second image mean that such events do not happen? Justify your answer.