1. Chapter 17 Study Guide Answers

2. the state of the atmosphere at a given time and place
1. What is weather?
the state of the atmosphere at a given time and place
- controlled by Earth’s motions & energy from the sun

3. 2. What is climate?
the given weather conditions of an area over many years
avg. rainfall
avg. temp
avg. humidity
avg. wind direction
avg. air pressure etc…

4. 3. What is the current composition of our atmosphere? Give gases & %
Current composition of atmosphere:
78% Nitrogen
21% Oxygen
0.93% Argon (inert gas)
0.039% Carbon Dioxide
Also present in atmosphere = water vapor, dust, ozone, and pollution

5. OZONE
4. O3 5. Found in the stratosphere- between km from surface, it increases the temperature 6. Blocks harmful Ultraviolet (UV) rays

6. 7. 4 layers of atmosphere
Troposphere = temperature decreases as you increase altitude
- Extends from surface to ~12 km
- All weather occurs here
Stratosphere = slight increase in temperature
- Extends from 12km to ~50 km
- Contains the Ozone Layer (absorbs UV to increase temperature)
Mesosphere = temperatures decrease with altitude
- No definite upper limit
- Temperatures near -90ºC
Thermosphere = temperatures increase due to absorption of high energy solar radiation

7. 8. What layer does weather occur?
Troposphere- all weather phenomena

8. 9. How much of the sun’s energy is reflected back into space?

9. 10. What is reflection?
When light bounces off an object

10. 11. What is scattering?
When weak light rays travel in different directions

11. 12. What is conduction?
Conduction = transfer of heat through direct contact of molecules
heat flows from the hotter object into the colder object

12. 13. What is convection?
Convection = transfer of heat by mass movement or circulation within a substance
heat from below (ground) conducts heat near the base of the atmosphere, the air

13. 14. What is radiation?
Radiation = heat is radiated (travels by waves) from the sun and hits the atmosphere
some radiated energy is absorbed and some is reflected (bounced) back into space:
~30% is reflected back into space
~50% is absorbed by land & sea
~20% is absorbed by clouds & atmosphere

14. 15. Greenhouse effect..why is it good?
Earth’s atmosphere naturally absorbs heat from the sun because of water vapor & carbon dioxide
atmosphere traps heat near the Earth’s surface
Without this natural greenhouse effect, Earth’s temperature would be much colder (uninhabitable for humans)

15. 16. Global warming…why is it bad?
Global warming is an increase in temp. of Earth’s atmosphere that may be caused by human activity
Affects overall climate and animal habitats

16. 17. 5 factors that influence temp. on Earth
Latitude
Heating of land & water
Altitude
Geographic position
Cloud cover

17. 18. How does latitude affect Earth’s temp?
Latitude (distance from the equator)
Differences in amount of solar radiation received
Variations in the angle of sun’s rays
Length of daylight

18. 19. Why do land & water have diff temps?
Land heats more rapidly and to higher temperatures than water
- Land also cools more rapidly and to lower temperatures than water
- Cities near water have a smaller daily temperature change compared to cities more inland

19. 20. What happens to temp. as you increase altitude
The higher the altitude, the colder the temperatures

20. 21. When does summer solstice occur?
On June 21 or 22

21. 22. When does winter solstice occur?
On December 21 or 22

22. 23. When does spring equinox occur?
March 21 or 22

23. 24. When does autumnal equinox occur?
September 22 or 23

24. 25. What is the tilt of Earth’s axis
23.5º

25. 26. What causes seasons?
The tilt of the Earth’s axis

26. Line on a map connecting points of equal temperature
27. What are isotherms?
Line on a map connecting points of equal temperature

27. 28. What is albedo?
Albedo- the fraction of total radiation that is reflected by any surface

28. 29. Clouds and keeping Earth cool & warm..
Day- clouds reduce radiation and keep it cooler. No clouds means it’s warmer.
Night- it’s the opposite; clouds act like a blanket & keep it warm. A clear night means it’s cooler