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Friday, 18 January 2008 06:46 |
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You know when you climb up a really big mountain. Why is it so cold and sometimes frozen up there if you're practically closer to the sun when you’re up there compared to being on normal ground?! Nico
Thanks for this great question Nico! It is cold on top of a mountain because heat is the result of energy being transferred from one body to another. When molecules collide with each other, some of the kinetic energy they have is converted to heat, so the more molecules there are in a defined space, the more often molecules collide and, therefore, the higher the measured temperature. On top of a mountain there are not many air molecules in the atmosphere, so there are not many collisions between them and it is cold. The effect of the sun on the atmosphere is to increase the kinetic energy of the molecules, making them more likely to collide with each other and at a greater velocity. This makes it hotter at low altitudes than at high altitudes, however, there is still some heat at high altitudes. Nevertheless, in the vacuum of space where there are hardly any molecules to collide with each other it is nearly -273 °C, which is very cold.
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