1. Chapter 15 questions

2. 1. Earth’s early atmosphere had little oxygen
1. Earth’s early atmosphere had little oxygen. How did oxygen come to make up 21% of Earth’s atmosphere?
Early organisms released oxygen into the air through photosynthesis.

3. 2. List the layers of the atmosphere in order beginning at Earth’s surface.
Troposphere
Stratosphere
Mesosphere
Thermosphere
Exosphere

4. 3. While hiking in the mountains, you notice that it is harder to breathe as you climb higher. Explain why this is so.
The air is thinner at the higher mountain altitudes because the pull of gravity is less. Therefore, there are fewer Oxygen molecules and more air is required.

5. 4. What are some effects from a thinning ozone layer?
Ozone helps protect the Earth from the Sun’s radiation. The thinning ozone layer allows more of the Sun’s radiation to hits Earth’s surface, causing more cases of skin cancer. Organisms, such as algae and plants, could be damaged resulting in less Oxygen in the atmosphere.

6. 1. How does the Sun transfer energy to Earth?
The Sun transfers energy through waves that don’t require a medium to transport through, which is radiation.

7. 2. How is Earth’s atmosphere different from the atmosphere on Mars?
Earth’s atmosphere is more dense, so it can hold in more of the sun’s heat.

8. 3. How is heat transferred from the stove to the water when you boil a pot of water?
Heat is transferred from the burner to the pot by direct contact, which is conduction. As the water heats, it begins to rise and transfers heat to the rest of the water through convection.

9. 4. Briefly describe the steps used in the water cycle.
Water evaporates from Earth’s surface, condenses into clouds and falls back to Earth as precipitation.

10. 1.Why do some parts of Earth’s surface, such as the equator, receive more of the Sun’s heat that other regions?
Earth’s curved surface causes solar energy to strike Earth at different angles. The more direct the angle, the greater the energy received.

11. 2. How does the Coriolis effect influence wind circulation on Earth?
Air masses in the northern hemisphere are deflected to the right, while those in the Southern hemisphere are deflected to the left.

12. 3. Why does little wind and lots of afternoon rain occur in the doldrums?
As air at the equator is warmed it is lifted and cooled (convection). This causes clouds and precipitation most afternoons.

13. 4. Which wind system helped early sailors navigate Earth’s oceans?
Sailors relied on the trade winds to navigate global trade routes.

14. Ultraviolet Radiation
Chlorofluorocarbons (CFCs) are dangerous because they destroy the hydrosphere.
Narrow belts of strong winds called sea breezes blow near the top of the troposphere.
The thin layer of air that surrounds Earth is called the troposphere.
Heat energy transferred in the form of waves is called condensation.
The ozone layer helps protect us from the Coriolis effect.
Ozone Layer
Jet
Streams
Atmosphere
Radiation
Ultraviolet Radiation