Earth’s Unequal Heating and Winds
Because Earth is a sphere and tilted on its axis, different regions on Earth receive different amounts of energy from the Sun. This uneven heating causes Earth’s surface and atmosphere to be warmer near the equator than near the poles. In the atmosphere, warmer air rises as cooler air sinks. This movement of air produces wind, which circulates and redistributes heat in the atmosphere.
Warm air near the equator rises; moves toward the poles and cools; sinks at about 30° N/S latitude; and flows back toward the equator, where it is warmed again. This circulation pattern, combined with the effect of Earth’s rotation, results in predictable wind patterns. At a certain latitude, the winds may flow toward the east or the west, depending on differences in temperature, pressure, altitude, and other such factors as swirling storm systems. For example, in the midlatitudes (roughly 30° to 60°N/S), surface winds flow from west to east and are called westerlies.
Play this video to observe the patterns of surface winds and how they flow across the globe.
| Keyboard Shortcut | Action |
|---|---|
| Space | Pause/Play video playback |
| Enter | Pause/Play video playback |
| m | Mute/Unmute video volume |
| Up and Down arrows | Increase and decrease volume by 10% |
| Right and Left arrows | Seek forward or backward by 5 seconds |
| 0-9 | Fast seek to x% of the video. |
| f | Enter or exit fullscreen. (Note: To exit fullscreen in flash press the Esc key. |
| c | Press c to toggle captions on or off |
- What patterns do you see in the winds?
- Where are some places that the winds mainly blow from south to north?
- How do you think the unequal heating of Earth's surface affects surface winds?
Produced by
