How Clouds Form

There are many different types of clouds, but they are all formed from the same basic mechanism. This mechanism is the rising motion of air. When a parcel of air rises it cools, due to the colder temperatures in the upper troposphere. The air itself is full of moisture, in the form of water vapor. As this moisture cools along with the air, it begins to condense onto tiny dust particles in the air. This condensation occurs at the boundary level known as the Lifting Condensation Level (LCL). This point is derived by computing the dew-point and temperature at the surface in a mathematical or graphical application. For the purpose of this article, know that the LCL is where moisture will condense. This essentially represents the cloud base. As the air continues to rise, more vapor condenses and begins to form water droplets. As these droplets begin to build up it forms a cloud. When the cloud becomes fully saturated with moisture, it lets it out in the form of precipitation. The cloud appears white due to the reflection of sunlight.

A cloud will not form unless enough initial moisture is present, and there is significant rising motion. This rising motion is a result of a few processes. First, un-even heating of the Earth's surface causes air to warm and rise (warm air is less dense and rises). Secondly air rises as a result of the terrain. If the winds are blowing towards a mountain range, the air is forces to rise up over these mountains. The rapid cooling of this air leads to clouds and heavy precipitation on the windward side(upslope), and dry calm weather on the leeward side(downslope). Another way air is forced to rise are low pressure systems. These massive areas of low pressure cause air to rise upward at the center, leading to clouds and precipitation. Fronts also cause air to be lifted.

There are many different classifications of clouds that deal with their appearance and location. High level clouds have the prefix "cirr-", such as cirrus clouds(the high wispy ones). Middle clouds have the prefix "alto-", such as alto-stratus. Low level clouds have no prefix. The main types of clouds that can form at any height are cirrus(high, white, wispy), cumulus(large, bumpy, flat-bottom), and stratus(flat layers that usually are gray and cover the sky).

The faster the air rises, the more powerful and violent these clouds become. Clouds associated with strong thunderstorms are known as cumulonimbus, and appear very dark and massive. These clouds have such momentum that they can reach the upper levels of the troposphere