Chapter 17
Study Guide Answers
1. What is weather?
the state of the atmosphere
at a given time and place
 - controlled by Earth’s
motions & energy from the
sun
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…
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

OZONE
4. O3
5. Found in the stratospherebetween 10-50 km from surface, it
increases the temperature
6. Blocks harmful Ultraviolet (UV)
rays
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
- No definite upper limit
8. What layer does weather occur?
 Troposphere- all weather phenomena
9. How much of the sun’s energy is reflected back
into space?
~30% is reflected back into space
10. What is reflection?
 When light bounces off an object
11. What is scattering?
When weak light rays travel in
different directions
12. What is conduction?
 Conduction = transfer of heat
through direct contact of molecules
 heat flows from the hotter object
into the colder object
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
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
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)
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
17. 5 factors that influence temp. on Earth
Latitude
Heating of land & water
Altitude
Geographic position
Cloud cover
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
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
20. What happens to temp. as you increase altitude
 The higher the altitude, the colder
the temperatures
21. When does summer solstice occur?
 On June 21 or 22
22. When does winter solstice occur?
On December 21 or 22
23. When does spring equinox occur?
March 21 or 22
24. When does autumnal equinox occur?
September 22 or 23
25. What is the tilt of Earth’s axis
23.5º
26. What causes seasons?
 The tilt of the Earth’s axis
27. What are isotherms?
Line on a map connecting
points of equal temperature
28. What is albedo?
Albedo- the fraction of total
radiation that is reflected by any
surface
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