cloud (thing)

Clouds are condensed or frozen atmospheric moisture. Fog is a specific type of cloud, but clouds are not a type of fog. The different types of clouds are:

• stratus - low altitude and smeared out
• stratocumulus - low altitude, half-smeared and half poofy
• cumulus - low to mid altitude, dome-shaped individual clouds
• mesostratus - mid altitude, smeared out in a layer, and decently thick
• cirrus - high altitude, wispy, and composed of ice crystals
• cirrostratus - high altitude, spread out in a layer
• cirrocumulus - high altitude, tiny and poofy
• stratonimbus - stratus that are producing precipitation
• cumulonimbus - cumulus that are producing precipitation

Other types of clouds include:

• gust front - a single line of stratonimbus in front of a thunderstorm
• mesocyclone - a thunderstorm that is slowly rotating; likely to produce tornados
• wall cloud - a slowly rotating cloud that hangs out the bottom of a thunderstorm, from which a funnel cloud can extend
• funnel cloud - a rapidly rotating funnel-shaped cloud that extends downward from a wall cloud in a thunderstorm; is not touching the ground
• tornado - a funnel cloud that has touched the ground
• tropical depression - a large system of clouds over a warm ocean that is a low-pressure system
• hurricane - a tropical depression that has gained in strength and wind speed

At the very basic level, clouds form when air that is relatively warm and moist cools down for some reason. In order for the water vapor to condense, condensation nuclei are required. The condensing process releases heat, which is part of how a thunderstorm is fueled. Dust and water droplets can serve as condensation nuclei. In order for the water droplets to freeze, an actual solid particulate matter of some sort is required. If it is not present, the droplets will become supercooled water - at a temperature below freezing, but still in a liquid state.

Coming soon: The Everything Guide to Weather