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:
Convection Lifting or
ConS Surface Heating
Frontal 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/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
Cloud Website
 http://www.2d-digital-art-guide.com/types-ofclouds.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
Picture should have
curls or wisps
http://www.enchantedlearning.com/subjects/astronomy/planets/earth/clouds/
Taller than
Stratocumulus
Drizzle, not
rain
Cloud Formation Worksheet p. 46
1. 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. C
11. B
5. A
12. A
6. E
13. B
7. B
14. C
8. Air Mass
15. False
9. A
10.B