11.3 CLOUDS AND PRECIPITATION

Main Idea- Clouds very in shape, size height of formation and type of precipitation.

LOOKING UP AT THE SKY

• Draw a picture of a cloud.•Do all clouds look the same?•Why are some clouds different than others?

CLOUD FORMATION•Forms when rising air mass cools•Earths surface is heated unevenly•As an air mass warms it becomes less dense than the surround air causing it to rise.•When it rises the pressure drops and causes the air to cool. •Water condenses around condensation nuclei

ATMOSPHERIC STABILITY•As an air mass rises it cools•Air masses will get continue to rise al long as it is warmer than the surround air. •Air that resists rising is stable

STABLE AIR•Depends on how temperature of the air mass changes relative to he atmosphere

• If the air cools faster than the surround atmosphere does with altitude than the air will sink back down.

• If it sinks back down than this is stable air and fair weather clouds may form

UNSTABLE AIR•Temperature of the surrounding air cools faster than the temperature of the rising air mass. •Air mass always less dense•Air mass will continue to rise•Produces types of clouds associated with thunderstorms

WHY DOES AIR RISE•Convection-warm air is less dense

WHY DOES AIR RISE?

•Orographic lifting- air is forced to raise over elevated land or topographic barriers like mountains

WHY DOES AIR RISE?

•Convergence lifting- air flows to same area from different directions•Some air is forced upward

TYPES OF CLOUDS

CLOUD NAMES

•Names of specific types of clouds are created by combining the name of the cloud's shape with the name of the cloud's height.

CLOUDS

There are 3 main types of clouds:

•Cumulus or fluffy clouds

•Stratus or layered clouds

•Cirrus or thin feathery clouds

Cumulus CirrusStratus

Cirrus

CIRRUS=HIGH CLOUDS

•The word cirrus comes from a Latin word and means a tuft or curl of hair. Cirrus clouds are very wispy and feathery looking.

CIRRUS CLOUDS•Cirrus generally occur in fair weather and point in the direction of air movement at their elevation.

LOW CLOUDS = STRATUS

•Stratus•Stratocumulus•Nimbostratus

Stratus Clouds

Low clouds are of made of water

droplets. However, when

temperatures are cold enough,

these clouds may also contain

ice particles and snow.

Stratus Clouds

Stratus Clouds

Stratus

The word stratus comes from the

Latin word that means "to spread

out." Stratus clouds are

horizontal, layered clouds that

stretch out across the sky like a

blanket.

STRATUS CLOUDS

•Stratus Clouds stretch across the sky in low, large flat layers. They resemble fog, but they do not reach the ground. They often produce mist or drizzle.

VERTICALLY DEVELOPED CUMULUS CLOUDS

•Fair weather cumulus have the appearance of floating cotton and have a lifetime of 5-40 minutes. The word cumulus comes from the Latin word for a heap or a pile. Cumulus clouds are puffy in appearance. They look like large cotton balls.

CUMULUS CLOUDS

•Harmless fair weather cumulus clouds can later develop into towering cumulonimbus clouds associated with powerful thunderstorms.

CUMULUS

•The clouds that produce heavy thunderstorms in summer are a form of cumulus clouds called cumulonimbus. Cumulonimbus clouds may extend upward for hundreds of meters.

FAIR WEATHER CUMULUS

WRITING ACTIVITY:

•Write a paragraph about one type of cloud. Include 3 or more facts about the cloud.

PRECIPITATION

PRECIPITATION

• Precipitation- all forms of water that fall to the ground

COALESCENCE

•Occurs when cloud droplets collide over and over again to form larger droplets.

•As this process continues droplets become to large and fall to the earth as precipitation

•Rain is precipitation that reaches earths surface in the form of a liquid.

•Rain can also begin as ice crystals that collect each other to form large snowflakes

•As the falling snow passes through the freezing level into warmer air, the flakes melt

HAIL

•Hail is formed when updrafts carry raindrops upwards into extremely cold areas of the atmosphere

HAIL

•There the raindrops merge and freeze. When the frozen clumps get to heavy they fall to earth

HAIL

•Hail can vary in size, from the size of a small stone to that of a baseball! So be careful

SLEET

•Sleet is frozen raindrops. Sleet begins as rain or snow and falls through a deep layer of cold air that contains temperatures below freezing that exist near the surface.

SLEET

•Rain that falls through this extremely cold layer has time to freeze into small pieces of ice

FREEZING RAIN

•Freezing rain is falling rain that cools below 0°C, but does not turn to ice in the air

•The water is “super cooled”

WHEN THE DROPS HIT ANYTHING THEY INSTANTLY TURN TO ICE!

SLEET AND HAIL

• https://www.youtube.com/watch?v=2-o4tr2Db2s

1. Nuclei for the formation of rain drops can be small particles of: A) salt, B) smoke, C) dust, D) all the above

2. Which of these cloud types is not based on the clouds shape: A) stratus, B) nimbus, C) cumulus, D) cirrus

3. Mid elevation clouds between 2000 and 6000m: A) nimbus, B) alto, C) cirri, D) strata

4. This form of precipitation is supercooled: A) rain, B) snow, C) sleet, D) freezing rain

5. This form of precipitation stays frozen all the way to the ground: A) rain, B) snow, C) sleet, D) freezing rain

Let’s see how you did!

THE ANSWERS!

1. D

2. B

3. B

4. D

5. B