Facts about Clouds!

The Basics

Clouds are large white or gray objects in the sky.

Clouds are a collection of very small drops of water or tiny pieces of ice that are held in the air.

A cloud is a mass of small water droplets or tiny ice crystals that float in the air.

Clouds are formed of water that has evaporated from rivers, lakes, oceans, or moist soil and plants. Some clouds are white and fleecy; others are dull gray or black sheets that darken the ground beneath them.

Most clouds continually move and change shape. Clouds change as parts evaporate in dryer air or they are moved and reshaped by wind and air currents.

Clouds are an important part of earth's weather.

Clouds carry water that falls to the earth's surface as rain and snow to then support all forms of life.

Clouds can sometimes bring destruction in the form of hail or tornadoes.

Understanding Clouds and Fog

Clouds are usually the most obvious feature of the sky.

They both reflect weather patterns and play a role in what the weather does.

Locations of Clouds

Low-level clouds, generally found below 6,500 feet. Low-level clouds are usually composed of liquid water droplets, but they can have snow and ice crystals in cold weather.

Mid-level clouds, generally found between 6,500 and 23,000 feet. Most mid-level clouds are composed of liquid water droplets during summer and a liquid droplet-ice crystal mix during winter. .

High-level clouds, generally found above 20,000 feet. High-level clouds are composed of ice crystals and tend to be very thin and wispy.

Different kinds of Clouds

Stratus clouds are uniform gray clouds that usually cover the entire sky.

They can form when very weak, upward vertical air currents lift a thin layer of air high enough to initiate condensation.

Stratus clouds also form when a layer of air is cooled from below to its dew point temperature and water vapor condenses into liquid droplets.

Stratus clouds look like a layer of fog that never reaches the ground.

Cirrus clouds are thin and high in the sky.

Cirrus clouds are thin, wispy clouds that usually form above 18,000 feet.

These clouds are blown by strong westerly winds aloft into streamers known as "mares' tails"

Cirrus clouds generally move from west to east across the sky and usually "point" to fair weather.

Cirrus clouds form when water vapour undergoes deposition and forms ice crystals.

Cirrus clouds are thin, because they form in the higher levels of the atmosphere where little water vapor is present.

Cumulus clouds are lumpy and can stretch high into the sky.

Cumulus clouds form as water vapour condenses in strong, upward air currents above the earth's surface.

These clouds usually have flat bases and lumpy tops. Cumulus clouds are usually very isolated with large areas of blue sky in between the clouds.

Most cumulus clouds form below 6,000 feet and are relatively thin and associated with fair weather. However, when the atmosphere becomes unstable and has very strong, upward air currents form, cumulus clouds can grow into Cumulus congestus, or Towering cumulus.

If the atmosphere is unstable enough, cumulonimbus clouds, better known as thunderstorms form. Cumulus congestus and Cumulonimbus clouds can tower from below 6,000 feet to greater than 50,000 feet.

Thunderstorms are cumulus clouds, sometimes called "thunderheads." Lightning is the key ingredient that defines a thunderstorms since lightning is needed to create thunder.

Mammatus clouds have pouches that hang down.

Mammatus clouds often form on the underside of cumulonimbus clouds, but are sometimes seen underneath other clouds as well.

They can appear threatening, but the sinking air required to make these clouds actually indicates weakening of the storm associated with them.

Mammatus are pouch-like clouds that protrude down from the bottom of a thunderstorm's anvil cloud.

Despite popular misconception, mammatus clouds usually are an indication severe weather has passed and thunderstorms are weakening. They are not a sign that a tornado is about to form.

However, mammatus clouds sometimes form on the upwind, or backside, of severe thunderstorms that at the same time are dropping large hail and unleashing 60-70 mph bursts of wind.