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Presentation on theme: "Clouds."— Presentation transcript:

1 Clouds

2 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.

3 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

4 Condensation Nucleii Tiny particle upon which condensation can occur.
Required for clouds to form. Examples: dust, chemicals, and bacteria Bathroom Mirror Condensation Nucleii

5 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

6 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.

7 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

8 2. Mountains – air is forced upwards as it runs into the higher terrain.
Also called Orographic Lifting

9 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)

10 Name the process responsible for forming clouds in each of the diagrams:
Convection Lifting or Surface Heating Frontal Lifting ConS

11 Convergence Lifting/Moving into a Low pressure area
Orographic/Mountain Lifting

12 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.

13 Cloud Worksheet - notes
Fill in the chart on pages 22 to 24 using the next few slides

14 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

15 Cumulus Clouds

16 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

17 Stratus Clouds

18 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

19 Nimbus Clouds

20 Cumulonimbus Cloud


22 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

23 Cirrus Clouds

24 Cloud Name/Prefix Quick 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

25 Cloud Website clouds.html



28 Cloud Formation p. 17

29 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

30 Worksheets: Clouds and What they Mean
Complete the 4 pages of worksheets p Omit Question 2 on page 25 See /pdfs/cl957-cvxak.pdf

31 Clouds and what they mean p. 27


33 Answer Key to page 25 Relative humidity Gas Evaporation dew point Fog

34 Page 26 Answer Key Cirrus Stratocumulus Altocumulus Nimbostratus
Cirrocumulus Cumulonimbus Stratus Altostratus Cumulus Cirrostratus

35 Answer Key page 27 Cirrus Cirrostratus Cirrocumulus Altocumulus
Altostratus Stratocumulus Stratus Nimbostratus Cumulus Cumulonimbus

36 Page 28 process that converts liquid to gas (liquid water to water vapor) temperature where water vapor in the air converts to liquid water drops % of water vapor in the air at a specific temperature and time. It can be increased by heating the air and by increased evaporation tiny water droplets or ice crystals ranging from below 2 kms to over 6kms above the ground.

37 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

38 Website _Formation_of_clouds_t9.html

39 Cloud in a jar See other powerpoint slides



42 Picture should have curls or wisps

43 Taller than Stratocumulus
Drizzle, not rain

44 Cloud Formation Worksheet p. 46
The warm air is rising, expanding and becoming less dense. As it cools, the moisture in the air condenses upon condensation nucleii, forming clouds The warm air is less dense and the cold air is pushing it up The mountain is causing the air to rise C B A A E B B C Air Mass False A B

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