A (very) rough guide to the physic involved "why there is snow on mountains" - by Wayne Naylor of www folgarida.co.uk
A snowball will melt if it is taken near to a fire and the nearer it gets the faster it melts, but climb a mountain (getting closer to the sun, which is very hot), you get colder and snow doesn't melt, WHY?
Fires produce light, hot gasses and radiation which warms the air around it, when you take some snow into this area of radiation, gas and heat it will start to melt back into water and eventually evaporate. If you move away or into a shadow the melting process slows down as the gases and heat diffuse (thin out) with distance. In contrast, the heat and hot gases produced by the sun pass through the vacuum of space, so there is no direct warming of the earth's atmosphere (or your lump of snow).
The sun releases (it does "not" create) energy due to gravity and pressure forcing hydrogen nuclei to fuse together to form a helium nucleus (well not exactly, but near enough for this) . As the new helium nucleus has less mass than the combined hydrogen nuclei it gets rid of the extra mass in the form of energy. Each second the sun converts around 680 million tons, (that's a "lot" of atoms) of hydrogen in helium and so… well lets just say it goes "bang". This electromagnetic energy radiates outwards in various forms such as heat, x-rays, light, gamma, radio waves, etc.
One form energy can be converted into another, so when this "Sun-Light" comes into contact with the earth it warms the ground, oceans and everything else and this energy is converted and re-radiated upwards as heat which (like the fire), warms the air. There is more air closer to the surface than higher up so, as you climb a mountain, the warming effect is lessened. When you're far enough away from the earth's surface the warming effect will be so reduced that the air is either the same temperature or lower than the snow and the snow will not melt.
BY Sohail Khan Luni
visit: www.sohailkhanluni.blogspot.com
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