Re: Heat of the Sun

Dear Mabel,

What a great question! I really had to think about this one.

You're absolutely right that the closer you get to the Sun, the hotter it gets. The temperature of the Sun's surface is 10,000 degrees Fahrenheit, and it's just like being closer to or further away from a fireplace, only more so. Planets that are closer to the Sun are hotter, and planets that are farther away are colder. People might some day be able to live on Mars (with a lot of help!) but the rest of the planets further away (Jupiter, Saturn, Uranus, Neptune) are too cold, and the two planets closer to the Sun (Venus and Mercury) are too hot. Earth is like Goldilocks's porridge, neither too hot or too cold, but "just right".

So, back to your question: Why does it get colder when you climb a mountain? Well, think about this: If you climb a mountain during the day, your location on Earth faces the Sun, so you're getting closer to the Sun as you climb. But when you climb a mountain at night, your location faces away from the Sun, so, as you climb, you're getting farther away. But, either way, you're still getting colder as you climb. Why?

It's because of our atmosphere! The surface of the Earth is warmed by the sun, and the heat from the Earth then heats the air that's in contact with it. The air that's not near sea level doesn't get to be heated as much by the Earth, because most of Earth's surface is near sea level, not on mountains. (If you flew higher than the highest mountain, the air gets colder still.)

The air near sea level mixes with the cooler air above it, so the temperature decreases gradually as your altitude increases.

The atmosphere is almost completely transparent, which means the Sun's rays pass through it with almost no effect. It's only by the Earth absorbing the Sun's rays, then the atmosphere being heated by the Sun-warmed Earth, that the atmosphere is warmed at all!

The atmosphere is actually even more complicated than I've told you so far. It's divided into five main layers, of which the trophosphere, the lowest one, is the one we've been talking about. Here's a good website that explains how the atmosphere works:

http://www.ducksters .com/science/atmosphere.php

Hope this helps!

Aaron