Unit 3: Earth’s Atmosphere Study Guide
Lesson 1: The Atmosphere

Composition, Air Pressure, and Temperature of the Atmosphere
1. Define atmosphere
a. Earth’s atmosphere is mixture of gases and is commonly called air
2. Identify the main components of Earth’s atmosphere
a. Earth’s atmosphere is composed mainly of nitrogen and oxygen. The remaining 1% is other gases.
3. Define air pressure
a. Caused by gravity
4. Describe how air pressure changes with altitude.
a. Decreases as distance from Earth’s surface increases.
5. Explain why temperature changes as altitude increases.
a. Air temperature changes as altitude increases.

Structure of the Atmosphere
1. List the four main layers of the atmosphere.
a. The troposphere is the lowest layer of Earth’s atmosphere. Temperature decreases as altitude
increases in this layer.
b. The stratosphere lies directly above the troposphere; it contains the ozone layer. Temperature
increases with altitude here.
c. The mesosphere is above the stratosphere. Temperature decreases with altitude here.
d. The thermosphere is the uppermost layer. Temperature increases with altitude here.
2. Identify the properties of each layer of Earth’s atmosphere.

Life and the Atmosphere
1. Describe how the atmosphere protects life.
a. Earth’s atmosphere protects life by reflecting or absorbing most of the sun’s radiation.
b. The ozone layer protects life by absorbing harmful ultraviolet radiation.
2. Describe how the atmosphere insulates the planet
a. The atmosphere maintains temperatures suitable for life and available liquid water.
b. The greenhouse effect is the warming of the surface and lower atmosphere of Earth.
Lesson 2: Energy Transfer

Temperature, Heat, Thermal Energy, Thermal Expansion
1. Define key terms.
a. Temperature measures the kinetic energy of an object.
b. Heat is energy transferred between objects.
c. Thermal Energy is the total kinetic energy of a substance.
d. Thermal expansion is when temperature increases and particles move faster and farther apart.
2. Describe what happens when objects at different temperatures come into contact.
a. Energy is transferred (as heat) from the warmer to the cooler object.

Radiation
1. Summarize the process of radiation.
a. Radiation is the transfer of energy as electromagnetic waves.
b. Radiation can occur between objects that are not touching
2. Identify the main source of energy on Earth’s surface.
a. The sun is the main energy source of the Earth
3. Identify examples of radiation on Earth.
a. Energy from the sun is absorbed by rocks, water, air, and living things.
b. That energy changes to thermal energy and is transferred to other parts of Earth’s systems.

Convection
1. Summarize the process of convection.
a. Convection is the transfer of energy due to movement of matter.
b. Convection occurs as a result of uneven heating of matter and thermal expansion and contraction.
2. Identify examples of convection on Earth.
a. Convection occurs most efficiently in liquids or gases, but also in solids, such as Earth’s mantle.
b. Convection currents form when hot matter rises and cool matter sinks.

Conduction
1. Summarize conduction
a. Conduction is the transfer of energy through a material.
b. Objects must touch for conduction to occur.
2. Identify examples of conduction on Earth.
a. Conduction occurs as water, rock, and air particles touch and transfer energy.
Lesson 3: Wind in the Atmosphere

The Movement of Air
1. Explain why air moves and identify the source of energy that cause air movement
a. Wind is air movement from an area of higher pressure to one of lower pressure.
b. Air moves due to density differences from uneven heating of the Earth’s surface.
c. The sun warms Earth and causes the circulation of air.
2. Illustrate how convection cells in Earth’s atmosphere cause high- and low- pressure belts at Earth’s surface.
a. Rising and sinking air in the atmosphere forms convection cells, which create high- and lowpressure belts on Earth.
3. Summarize the Coriolis effect.
a. The Coriolis effect is the curving of he path of a moving object as a result of Earth’s rotation.
b. Wind curve to the right in the Northern Hemisphere; left in the Southern


Global Winds
1. List two factors that produce global winds.
a. Pressure belts and the Coriolis effect produce global winds.
2. Identify and locate the three major global wind systems.
a. The major wind systems are the easterlies, westerlies, and trade winds.
b. Polar easterlies blow east to west.
c. Mid-latitude westerlies blow west to east.
d. Tropical trade winds blow east to west.
e. The doldrums and horse latitudes are zones with weak, variable winds located at 30o north and
south latitudes and the equator.
3. Describe winds where global pressure belts meet.
4. Define jet streams.
a. Jet streams are bands of high-speed winds in the upper troposphere
Local Winds
1. Explain how differences in the way land and water absorb and release energy cause local winds, such as sea,
land, valley, and mountain breezes.
a. Local wind move short distances and are variable in direction.
b. Most local winds are caused by differences I pressure, in turn caused by differences in pressure, in
turn caused by uneven heating of Earth’s surface.
c. Land and water absorb and release energy differently, resulting in local air pressure differences
which cause sea and land breezes and mountain and valley breezes.