Clouds

What are Clouds?

Clouds are made of water.

They are either made up of small liquid water drops or tiny ice crystals.

Meteorologists are scientists who study the weather, including clouds.

A few other terms

Relative Humidity – is the % of water vapor in the air compared to how much it can hold at that temperature

Dew Point - is the temperature

when water vapor turns to liquid

Evaporation – the change from

liquid to gas

Condensation – the change from

gas to liquid

Condensation Nucleii

Tiny particle upon which condensation can occur.

Required for clouds to form.

Examples: dust, chemicals, and bacteria

Bathroom Mirror

Clouds and Levels

Low-level clouds are found below 2 km

Mid-level clouds are situated from 2 to 6 km high & have the prefix ALTO

High-level clouds are above 6 km in altitude

How do Clouds Form?

Basically clouds form as warm air at the surface of the earth rises.

As the parcel of air rises into the atmosphere, it cools.

Cool air cannot hold as much water vapor as warm air, so at a certain cool temperature, the water vapor condenses out of the air and forms clouds.

There are several ways that a parcel air can be forced to rise:

1. Surface Heating – the sun warms the air and then the warm air rises because it is less dense.

Also called Convective Lifting

2. Mountains – air is forced upwards as it runs into the higher terrain.

Also called Orographic Lifting

3. Fronts - When an air mass of one temperature meets another, the warmer air mass will rise over the cooler air mass. (Frontal Lifting)

4. Air Pressure - When an air mass moves into a lower pressure area, the air will force the air that was there before, upwards. (Convergence Lifting)

Name the process responsible for forming clouds in each of the diagrams:

ConSConvection Lifting or

Surface HeatingFrontal Lifting

Convergence Lifting/Moving into a Low pressure area

Orographic/Mountain Lifting

Fun Facts

Advection cooling - When an air mass cools down because the air mass has moved into a cooler area or on top of a cooler surface.

Adiabatic cooling - When air rises it cools. Air temperature decreases with increasing elevation. Usually associated with Orographic (mountain) lifting.

Cloud Worksheet - notes

Fill in the chart on pages 22 to 24 using the next few slides

Cumulus Clouds – page 22

They have a fluffy, puffy or billowy appearance, much like cotton balls or cauliflower heads, often very white in color.

They are made of tiny water droplets that occur in clumps which then rapidly rise when the sun heats them

They are associated with fair weather and blue skies

Cumulus clouds are found at all altitudes

Cumulus Clouds

Stratus Clouds – page 22

These are featureless sheet-like clouds, usually grey in color

They are made from a huge amount of fine water droplets called water vapor

These clouds produce overcast skies, light mist or drizzle

They occupy low altitudes

Stratus Clouds

Nimbus Clouds – page 23

Can take on many different appearances, often puffy and either white or grey. Often called Storm clouds.

Made up of a large amount of large water droplets

Create heavy rain or snow

Found at low levels

Nimbus Clouds

Cumulonimbus Cloud

Cirrus Clouds –page 23

Delicate looking, often wispy, curly, feathery, like horsetails

Made up of ice crystals

May occur when weather is nice, but sign of bad weather to come

They occur at high altitudes

Cirrus Clouds

Cloud Name/PrefixQuick Reference – page 24

Cumulo – puffy – all levels

Stratus – layers – all levels

Cirrus – wispy – high level

Nimbus – precipitation – all 3 shapes - all levels

Alto – all 3 shapes – middle level

Cloud Website http://

www.2d-digital-art-guide.com/types-of-clouds.html

Cloud Formation p. 17

Cloud Formation - summary

Warm air rises and cools

The water vapor in the air condenses to liquid water droplets

To do so, condensation nucleii are needed

Particles of dust, pollen or smoke provide a cool surface upon which the water vapor can condense on

Worksheets:Clouds and What they Mean

Complete the 4 pages of worksheets p. 25 - 28

Omit Question 2 on page 25

See http://www.powermediaplus.com/furtherlearning/pdfs/cl957-cvxak.pdf

Clouds and what they mean p. 27

Answer Key to page 25

A. Relative humidity

B. Gas

C. Evaporation

D. dew point

E. Fog

F. Precipitation

Page 26 Answer Key

1. Cirrus

2. Stratocumulus

3. Altocumulus

4. Nimbostratus

5. Cirrocumulus

6. Cumulonimbus

7. Stratus

8. Altostratus

9. Cumulus

10. Cirrostratus

Answer Key page 27

1. Cirrus

2. Cirrostratus

3. Cirrocumulus

4. Altocumulus

5. Altostratus

6. Stratocumulus

7. Stratus

8. Nimbostratus

9. Cumulus

10. Cumulonimbus

Page 28

1. process that converts liquid to gas (liquid water to water vapor)

2. temperature where water vapor in the air converts to liquid water drops

3. % of water vapor in the air at a specific temperature and time. It can be increased by heating the air and by increased evaporation

4. tiny water droplets or ice crystals ranging from below 2 kms to over 6kms above the ground.

Page 28

5. Condensation nuclei (dust particles) are needed for the water vapor to condense on and warm air must rise

6. Cumulus

7. Nimbostratus (or just stratus)

8. Cumulonimbus (present during thunderstorms)

9. a. Precipitation (rain or snow)

b. Middle

c. Sheet; Layers

10. Rain, snow, sleet, hail or mist

Website

http://www.atmosphere.mpg.de/enid/1__Clouds/-_Formation_of_clouds_t9.html

Cloud in a jar

See other powerpoint slides

http://www.enchantedlearning.com/subjects/astronomy/planets/earth/clouds/

Picture should have curls or wisps

Taller than Stratocumulus Drizzle, not

rain

Cloud Formation Worksheet p. 461. The warm air is rising, expanding and becoming less dense. As it cools, the moisture in the air condenses upon condensation nucleii, forming clouds

2. The warm air is less dense and the cold air is pushing it up

3. The mountain is causing the air to rise

4. C11. B

5. A12. A

6. E13. B

7. B14. C

8. Air Mass 15. False

9. A

10.B