A cloud is a large collection of
very tiny droplets of water or ice crystals. The droplets are so small and
light that they can float in the air. All air contains water, but near the
ground it is usually in the form of an invisible gas called water vapor. When
warm air rises, it expands and cools. Cool air can't hold as much water vapor
as warm air, so some of the vapor condenses onto tiny pieces of dust that are
floating in the air and forms a tiny droplet around each dust particle. When
billions of these droplets come together they become a visible
Clouds are white because they
reflect the light of the sun. Light is made up of colors of the rainbow and
when you add them all together you get white. The sun appears a yellow color
because it sends out more yellow light than any other color. Clouds reflect all
the colors the exact same amount so they look white. Clouds are made up of tiny
water droplets or ice crystals, usually a mixture of both. The water and ice
scatter all light, making clouds appear white. If the clouds get thick enough
or high enough all the light above does not make it through, hence the gray or
dark look. Also, if there are lots of other clouds around, their shadow can add
to the gray or multicolored gray appearance.
A cloud is made up of liquid
water droplets. A cloud forms when air is heated by the sun. As it rises, it
slowly cools it reaches the saturation point and water condenses, forming a
cloud. As long as the cloud and the air that its made of is warmer than the
outside air around it, it floats!
Clouds move with the wind. High
cirrus clouds are pushed along by the jet stream, sometimes traveling at more
than 100 miles-per-hour. When clouds are part of a thunderstorm they usually
travel at 30 to 40 mph. The characteristics of clouds are dictated by the
elements available, including the amount of water vapor, the temperatures at
that height, the wind, and the interplay of other air masses.
There are many different types of
fog, but fog is mostly formed when southerly winds bring warm, moist air into a
region, possibly ending a cold outbreak. As the warm, moist air flows over much
colder soil or snow, dense fog often forms. Warm, moist air is cooled from
below as it flows over a colder surface. If the air is near saturation,
moisture will condense out of the cooled air and form fog. With light winds,
the fog near the ground can become thick and reduce visibilities to zero.
|You need warm air! Southerly winds bring warm, moist air
over cold ground or snow.
||Fog Forms! Moisture condenses into fog as air is cooled
|High Clouds =
|Middle Clouds =
||6,500 feet to 18,000
|Low Clouds =
||Up to 6,500 feet
|Clouds with Vertical
clouds are the most common of the high clouds. They are composed of ice and
are thin, wispy clouds blown in high winds into long streamers. Cirrus clouds
are usually white and predict fair to pleasant weather. By watching the
movement of cirrus clouds you can tell from which direction weather is
approaching. When you see cirrus clouds, it usually indicates that a change in
the weather will occur within 24 hours.
clouds are thin, sheetlike high clouds that often cover the entire sky.
They are so thin that the sun and moon can be seen through them. Cirrostratus
clouds usually come 12-24 hours before a rain or snow storm.
clouds appear as small, rounded white puffs that appear in long rows. The
small ripples in the cirrocumulus clouds sometime resemble the scales of a
fish. Cirrocumulus clouds are usually seen in the winter and indicate fair, but
cold weather. In tropical regions, they may indicate an approaching hurricane.
are gray or blue-gray mid level clouds composed of ice crystals and water
droplets. The clouds usually cover the entire sky. In the thinner areas of the
clouds, the sun may be dimly visible as a round disk. Altostratus clouds often
form ahead of storms with continuous rain or snow.
are mid level clouds that are made of water droplets and appear as gray puffy
masses. They usually form in groups. If you see altocumulus clouds on a warm,
sticky morning, be prepared to see thunderstorms late in the
|Stratus clouds are
uniform grayish clouds that often cover the entire sky. They resemble fog that
doesn't reach the ground. Light mist or drizzle sometimes falls out of these
are low, puffy and gray. Most form in rows with blue sky visible in between
them. Rain rarely occurs with stratocumulus clouds, however, they can turn into
form a dark gray, wet looking cloudy layer associated with continuously falling
rain or snow. They often produce precipitation that is usually light to
|Cumulus clouds are
white, puffy clouds that look like pieces of floating cotton. Cumulus clouds
are often called "fair-weather clouds". The base of each cloud is flat and the
top of each cloud has rounded towers. When the top of the cumulus clouds
resemble the head of a cauliflower, it is called cumulus congestus or towering
cumulus. These clouds grow upward and they can develop into giant cumulonimbus
clouds, which are thunderstorm clouds.
are thunderstorm clouds. High winds can flatten the top of the cloud into an
anvil-like shape. Cumulonimbus clouds are associated with heavy rain, snow,
hail, lightning and even tornadoes. The anvil usually points in the direction
the storm is moving.
|Mammatus clouds are
low hanging bulges that droop from cumulonimbus clouds. Mammatus clouds are
usually associated with severe weather.
|Lenticular clouds are
caused by a wave wind pattern created by the mountains. They look like discs or
flying saucers that form near mountains.
|Fog is a cloud on the
ground. It is composed of billions of tiny water droplets floating in the air.
Fog exists if the atmospheric visibility near the Earth's surface is reduced to
1 kilometer or less.
condensation trails left behind jet aircrafts. Contrails form when hot humid
air from jet exhaust mixes with environmental air of low vapor pressure and low
temperature. The mixing is a result of turbulence generated by the engine
|Green Clouds are
often associated with severe weather. The green color is not completely
understood, but it is thought to have something to do with having a high amount
of liquid water drops and hail inside the clouds. In the Great Plains region of
the U.S. green clouds are associated with storms likely to produce hail and