When water evaporates from the earth's surface, the vapor rises, cools and condenses into water droplets, and gives rise to the clouds, which are agglomerations of liquid droplets and ice crystals. There are several ways of cooling the air: slope upward motion when the air goes up a long slope, by contact, when warm air collides with a colder surface, and clouds are light and large, vertical convection, due to the action of the winds which raise the unstable air or by heating the air in contact with the surface of the Earth and its subsequent rise, individual processes that form clouds. Clouds can be classified according to their height in high, medium, low and vertical development. Among the former, which are at a level below half of 6100 meters, there are cirrus, and cirrostratus cirrocumulus. The altocumulus and altostratus belong to the middle clouds, located at an average height of less than 900 meters. Among the low clouds, located at a level below half close to the ground, are stratocumulus, stratus and nimbostratus. Finally, among the clouds of vertical development, with a lower level is 500 meters, are clusters and cumulonimbus.
Turbulence and the formation of ice on the wings, tail and propeller aircraft are the most common risks faced by drivers when they cross certain clouds.
The wind moves faster than the clouds and incorporates a certain amount of water vapor, forming new particles.