To UNDERSTAND the philosophy of this beautiful and often sublime phenomenon, so often witnessed since the flood, a few facts derived from observation, and a long train of experiments must be observed: 

1. Were the atmosphere, everywhere, at all times, at a uniform temperature, we should never have rain, or hail, or snow; the water absorbed by its evaporation from the sea and the earth's surface, would descend in an impenetrable vapor, or cease to be absorbed by the air when it once became fully saturated.

2. The absorbing power of the atmosphere, and consequently its capability to retain moisture, is proportionately greater in cold than in warm weather.

3. The air near the surface of the earth is warmer than in the region of the clouds. 

The higher we ascend from the earth, the colder we find the atmosphere. Hence the perpetual snow on every high mountain in the hottest climates. Now, when from continual evaporation, the air is highly saturated with vapor, though it be invisible, and the sky cloudless, if its temperature is suddenly reduced by cold currents of air rising from a higher to a lower latitude, its capacity to retain moisture is diminished, clouds are formed, and the result is rain. 

Air condenses as it cools, and, like a sponge filled with water and compressed, pours out the water which its diminished capacity cannot contain.

 Democratic Advocate.