Why the equator is warmer than the poles
The Sun shines on the whole Earth, but not equally. Near the equator the Sun’s rays hit the ground almost straight on, so the same amount of sunlight is packed into a small area and heats it strongly. Farther away from the equator the rays arrive slanted. The same beam spreads over a bigger area, so each part gets less heat. That is why the Earth has a hot band around the equator, moderate bands in the middle, and cold regions near the poles. Egypt lies in the middle, so it is hot in summer and mild in winter. The ground absorbs the sunlight first and then warms the air above it. This difference in heating also affects rain: many of the world’s big deserts, including the Sahara, lie where dry air sinks.
| Region | Sun’s rays | Area heated by the beam | Temperature |
|---|---|---|---|
| near the equator | almost straight | small | hot |
| middle bands | a little slanted | larger | moderate |
| near the poles | very slanted | very large | cold |
| Torch | Patch on the wall | Brightness |
|---|---|---|
| straight | small | bright |
| tilted | big | dim |
Torch and wall. In a dim room, with a grown-up, shine a torch straight at a wall, then tilt it. Draw the patch each time. Which patch is brighter? Never shine the torch into anyone’s eyes. Say how this helps explain the hot and cold bands on Earth.