Download Chapter 18 Worksheets

Chapter 18
Water in the Atmosphere
18.1 Humidity and condensation
While you read:
1. List and describe the three states of water.
Solid: ice, snow, and hail; temperatures of 0ºC
or below.
Liquid: rain, cloud droplets; temperatures
between 0ºC and 100ºC
Vapor: bubbles in boiling water; temperatures of
100ºC or higher
While you read
2. Write two sentences comparing and
contrasting specific and relative humidity. Tell
how each is measured.
Specific humidity measures the amount of water
vapor actually present in the air while relative
humidity measures how close the air is to
saturation. Specific humidity is measured in
grams of water vapor/kg of air while relative
humidity is stated as a percentage.
After you read
1. Contact with colder surface: causes
condensation on that surface.
2. Radiation: ground loses heat and cools the
air above, leaving droplets of water in the
air that take time to fall.
3. Mixing: warm air blows over cold ground,
cooling the air and lowering it below the
dew point.
4. Condensation: change from vapor to liquid
when air cools beyond its saturation point.
5. Condensation nuclei, tiny particles around
which condensation can accumulate.
Chapter 18.2
Clouds
While you read
• Cirrostratus: high altitude; horizontal;
thin sheets that may suggest
precipitation
• Cirrocumulus: high altitude; vertical;
puffy clouds especially in winter
• Altostratus: middle altitude; horizontal;
similar to cirrostratus
Cirrostratus
Altostratus
Nimbostratus
Cirrocumulus
Altocumulus
Stratocumulus
Cumulonimbus
Cumulonimbus
• Altocumulus: middle altitude; vertical; similar
to cirrocumulus
• Nimbostratus: low altitude; horizontal; dark
gray layers of cloud that produce steady rain
• Cumulonimbus/cumulus: can span many
altitudes; vertical; cumulonimbus produce
heavy rain with thunder and lightning.
After you read
• Altostratus clouds form as air rises and
cools in layers. These layers form when
the surrounding air is stable and forces
rising air to move horizontally rather
than vertically.
18.3 Precipitation
While you read
1. Rain: water droplets that have become big
enough to fall to the ground.
2. Sleet: forms when rain falls into a layer of
cold air
3. Freezing rain: forms when raindrops freeze
instantly when they hit a solid surface
4. Hail: forms when a frozen raindrop or clump
of ice crystals is blown back up repeatedly,
building up layers of ice before falling to the
ground
5. Snow: forms when ice crystals in a cloud
collide and clump together.
After you read
• Precipitation forms in areas where air rises
and produces condensation. These areas
include places near the equator where the
sun’s heat raises land temperatures, places
with low pressure where storms are common,
and places where moist air rises over
mountains and then cools.
• Dryness occurs in places where air sinks and
warms. These places include areas of
persistent high pressure, areas with
extremely cold temperatures, and areas on
the leeward side of mountains where dry air
Windward vs. Leeward
Chapter 18 Test: Essay Study
Guide
• What types of clouds will form when a body of warm,
moist air rises to a region of dry, stable air? Explain
why and how they form.
Cumulus clouds will form.
Cumulus clouds grow vertically.
Warm air rises and cools, causing condensation.
Clouds grow upward until temperature and density of
inside of cloud is same as outside air.
• Explain how ice crystals grow in a cloud. Under
what conditions will ice crystals fall as snow?
Under what conditions will the ice crystals form
hail?
Upper layers of clouds contain ice crystals and
super-cooled droplets. As super-cooled
droplets evaporate, the water vapor is
deposited on ice crystals. Heavy crystals fall,
clumping together to form snow.
If the snow doesn’t fall through a layer of warm air
that melts it into rain, it may reach the ground
as snow .
Hail forms when a growing ice crystal is kept aloft
by updrafts and continues to grow into a large
ice clump. Bonus points: As the hail is carried
up it then refreezes adding to its diameter.
Show a drawing depicting this concept.