Latitude

What creates all these climates? Several factors. The first is latitude.

Latitude measures distance from the Equator, going up as you move north or south. Near the Equator (low latitudes) it's hot; going towards the poles (high latitudes) it becomes temperate, then cold.

Why? Because of the angle of the sun's rays.

• At the Equator, rays hit almost straight down, so their energy falls on a small area.
• Near the poles, rays come in slanting, so the same energy spreads over a bigger area.

Try it with a torch: shine it straight down on a table and you get a small bright circle. Tilt it and the light spreads into a long, dim oval. Same light, more area, less heat in each spot.

There's a second reason: a slanting ray travels through more of the atmosphere before it lands, losing more energy on the way.

So the poles get less heat than the Equator. In India too: Kanniyakumari and the Nicobar Islands, close to the Equator, are warm or hot nearly all year; Srinagar in the north is much cooler.