Warm-Up Atmospheric Moisture and Precipitation

?

© Edgenuity, Inc. 1

Lesson Goals

Lesson Question

Words to Know

Write the letter of the definition next to the matching word as you work through the lesson. You may use the glossary to help you.

dewpoint A. a thin, wispy cloud made of ice crystals that forms at high elevations

B. the amount of water vapor in the air relative to the amount the air can hold

C. a fluffy, rounded cloud that forms at lower elevations

D. the temperature at which water vapor in the air condenses and forms droplets

E. the measure of water vapor in the air

F. a thick cloud at or near Earth’s surface

G. a low-level cloud characterized by horizontal layering with a uniform base

cirrus cloud

relative humidity

cumulus cloud

stratus cloud

humidity

fog

WK2

Describehumidity and how

it is measured.

Explain how

clouds form.

Identify common

types of

precipitation.

Distinguish the

main types of

clouds.

Warm-Up Atmospheric Moisture and Precipitation

© Edgenuity, Inc. 2

The Water Cycle

Life on Earth could not exist without water or the water cycle.

• This is the process of water through the air, land,

and .

• Surface water evaporates into the .

• The water vapor condenses and falls back to Earth’s surface as

.

Atmospheric Moisture and Precipitation

© Edgenuity, Inc. 3

Humidity

Humidity is the measure of the amount of water in the air.

Relative Humidity

Relative humidity is the amount of

vapor in the air relative to

the amount the can hold.

• air holds more

moisture than air.

• Warmer air promotes more

.

• Areas with a large amount of

surface water have levels of humidity.

2Slide

Instruction

Air that has low humidity is very

, like desert air and

winter air.

Warm air can hold more water vapor,

giving it humidity, like

rainforest air.

Atmospheric Moisture and Precipitation

© Edgenuity, Inc. 4

Dew and Frost

For water vapor to condense, particles must be present in the air.

• Water droplets and ice crystals can form on:

• particles of dust, salt, and smoke.

• solids such as grass and windows.

• water that condenses is dew.

• ice that condenses is frost.

Instruction

Water Condensation

Clouds form when water vapor in air to form liquid water or ice.

• As air cools, it cannot hold as much water .

• Water vapor cools with the air and condenses into water droplets or ice.

• The temperature at which condensation happens is called point.

5Slide

Atmospheric Moisture and Precipitation

© Edgenuity, Inc. 5

8Slide

Types of Clouds

Cirrus Clouds

Cirrus clouds are thin and wispy. They form at high altitudes where

are low.

• Cirrus clouds form at high altitudes and are made of crystals.

• Cirrocumulus clouds are small and puffy and appear in .

Instruction

Types ofClouds

Cirruscloud

Stratuscloud

cloud

Atmospheric Moisture and Precipitation

© Edgenuity, Inc. 6

Instruction

8Slide

Cumulus Clouds

Cumulus clouds are and .

• Form close to the , only about 1–1.5 miles up in the sky

• Can extend to more than miles up in the sky to form a cumulonimbus cloud

Stratus Clouds

Stratus clouds form in large layers.

• Are usually dull in color

• Cover all or most of the sky

• May produce drizzle, rain, or snow

• Nimbostratus clouds

Atmospheric Moisture and Precipitation

© Edgenuity, Inc. 7

Instruction

8Slide

Types of Precipitation

PrecipitationSnow

RainSleet

Hail

rain

Fog

that form at or near the ground are called fog.

• Fog forms when the ground cools at night after a warm, humid day.

• The air is just above the dew point.

• Fog is more common in areas near bodies of water.

• Fog “burns off” when sunlight causes water droplets

to .

11

Atmospheric Moisture and Precipitation

© Edgenuity, Inc. 8

Instruction

11Slide

Snow

Snow is ice crystals that fall from .

• Water vapor in clouds is converted directly into ice crystals.

• These ice crystals are called .

• Snowflakes form around particles in the atmosphere.

Hail

Hail is round pellets of that fall from clouds.

• The pellets of ice are more than 5 mm in diameter.

• Hail forms in cumulus clouds during .

• Pellets are tossed up and down in clouds, gaining layers of ice and growing larger.

• The ice pellets become too heavy and fall to the ground.

Rain

Rain is the most common form of .

• is raindrops that freeze into ice pellets less than 5 mm in

diameter.

• Freezing rain occurs when rain touches a cold surface and freezes.

Atmospheric Moisture and Precipitation

Lesson Question

© Edgenuity, Inc. 9

2Slide

?

Summary

Review: Key Concepts

is the measure of the amount of water vapor in the air. Relative

humidity is the amount of vapor in the air relative to the amount the air can hold.

Answer

Lesson Question

What is the role of atmospheric moisture in the formation of clouds and precipitation?

Types of Cloud Formation

Types of

• Clouds need cool air and tiny particles on which water vapor can condense.

• Cirrus – thin, wispy

• Cumulus – round, fluffy

• Stratus – cover the sky

• Fog – clouds on the surface

• Rain

• Sleet

• Freezing rain

• Snow

• Hail

Summary Atmospheric Moisture and Precipitation

© Edgenuity, Inc. 10

Use this space to write any questions or thoughts about this lesson.