# Unit C, Chapter 3, Lesson 1

```Chapter Outline
Unit C, “Processes That Change the Earth”
Chapter 3, “Weather and Climate”
Lesson 1, “How Can You Observe and Measure Weather Conditions?”, pgs. C64-C69
Where Weather Occurs
Define Atmosphere – layers of air that surround the Earth
Almost all weather occurs in the ____lowest layer___________. This is called the
____troposphere___________. This is where most _____water__________ is found and
where most _______clouds________ form.
The layer of atmosphere above the troposphere is called the …
Stratosphere
The ______ozone layer_________ protects life on Earth by absorbing some of the sun’s
harmful rays.
Measuring Atmospheric Conditions
Why does the weather change?
The atmosphere is constantly changing
Define Air Pressure – the weight of the air
Define Humidity – the amount of moisture in the air
Name three instruments used to measure atmospheric conditions and what they measure:
1.Rain Gauge, measures the amount of precipitation
2.Thermometer, measures air temperature
3.Barometer, measures air pressure
Define Precipitation – any form of water that falls from clouds
Why do people measure atmospheric conditions?
To predict what the weather will be
Air Pressure
The atmosphere pushes on you all the time, and this weight is _______air
pressure________.
What instrument is used to measure air pressure?
Barometer
________Warm_______ air weighs less than _____cold__________ air.
A mass of cold air is called a ________high-pressure area_______.
A mass of warm air is called a _________low-pressure area______.
What probably will happen if the barometer is rising? What probably will happen if the
barometer is falling?
If the barometer is rising, the weather will become fair.
If the barometer is falling, the weather will become stormy.
Water In the Air
What is humidity?
The amount of water or moisture in the air.
Define Evaporation – when liquid water changes into water vapor from the heat of the
sun
Define Condensation – when water vapor changes back into liquid water, typically high
in the atmosphere, and forms clouds
The transferring of water from the Earth’s surface to the atmosphere and back is called …
Water cycle
Water vapor that condenses near the ground, forming a cloud, is called
_________fog______.
Weather scientists are called _______meteorologists ________.
List three basic names of clouds:
Cumulus, Cirrus, Stratus
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