Transcript Clouds - Holy Family Regional School

Clouds
What are clouds?
A cloud is made up of tiny water
droplets and they form when
water vapor in the air becomes
liquid water or ice crystals.
What do clouds tell us?
The presence of clouds in the
sky is one type of signal to
meteorologists that there will be
changes in the weather.
How do they form?
Clouds form whenever air
is cooled to its dew point
and particles are present
Identifying Clouds
Meteorologists identify clouds based on five
basic cloud characteristics:
1. The altitude at which they occur
2. Color
3. Density
4. Shape
5. Degree of cover.
From this information, we can
identify three basic cloud
types and seven other common
cloud types.
Three main types:
• Cumulus
• Stratus
• Cirrus
Cumulus
Fluffy clouds indicating fair
weather
Cumulus or fluffy clouds
form when air is forced
up rapidly and therefore
rises higher
Puffy white or light gray
clouds that look like
floating cotton balls.
Cumulus clouds have
sharp outlines and a flat
base.
Cumulonimbus
Often produce thunderstorms
Can grow up to 10km
high.
High winds make the
top of the cloud flat.
Cumulonimbus clouds
can produce heavy
rain, hail, lightning, and
tornadoes.
Clouds with Vertical Development
Cumulus and Cumulonimbus
(surface to 13,000 m)
The clouds develop by warm air rising from the
surface.
Cumulus and Cumulonimbus clouds provide the
most interesting and severe weather to our planet.
cumulonimbus
Altocumulus
(middle 2,000 to 7, 000 m)
Middle clouds are made of
ice crystals and water
droplets.
They are grayish-white with
one part of the cloud darker
than the other.
Usually form in groups.
If you see altocumulus clouds
on a warm sticky morning, then
expect thunderstorms by late
afternoon.
Stratus
low surface to 2000 m
Clouds that form in flat layers
Stratus, Nimbostratus
and Stratocumulus
Low clouds are made up of water droplets.
Stratus clouds are formed when air is
forced up slowly.
The base of a low cloud is from the ground
to 2000 m.
Nimbostratus
As stratus clouds thicken, they may
produce drizzle, rain, or snow.
Altostratus
(middle 2,000 to 7, 000 m)
Middle clouds are made of ice
crystals and water droplets.
An altostratus cloud usually covers
the whole sky.
The cloud looks gray or blue-gray.
Usually forms ahead of storms that
have a lot of rain or snow.
Sometimes, rain will fall from an
altostratus cloud.
Stratocumulus:
•Groups of dense, puffy clouds that cover the
sky in dark heavy masses, long and gray. They
often form in bands across the sky.
Cirrus
(high 5000-16,000 m)
Wispy, feathery clouds made mostly
of ice crystals
• Cirrus clouds are usually white and
predict fair weather and point in the
direction of air movement .
•Cirrus clouds are the first sign of an
approaching storm.
They are the highest of all the clouds.
Cirrocumulus
Look like rows of cotton balls
which indicate a storm is on its way
Cirrocumulus are usually white, but
sometimes appear gray.
Cirrocumulus are usually seen in the
winter time and mean that there will be
fair, but cold weather.
Cirrostratus
Sheet - like thin clouds that usually
cover the entire sky.
Cirrostratus clouds usually come 12-24
hours before a rain or snow storm
Fog
Clouds that form at or near the ground
Cloud Type by Rain
Nimbus – any cloud that rains
Cumulonimbus
taller, towering versions
of cumulus clouds.
Their height can be
from two to five miles.
These clouds often
form thunderstorms.
Nimbostratus:
low, flat, dark gray
clouds that are
associated with steady
precipitation and
occur in thick,
continuous layers.
Cumulonimbus Clouds as seen
from Apollo 8