Prentice Hall Earth Science chapter 17 layers of the atmosphere and solar radiation.

1. Prentice Hall
EARTH SCIENCEEARTH SCIENCE
Tarbuck Lutgens

2. Chapter
1717
The Atmosphere: Structure
and Temperature

3. Composition of the Atmosphere
17.1 Atmosphere Characteristics
 Weather is constantly changing, and it
refers to the state of the atmosphere at any
given time and place. Climate, however, is
based on observations of weather that have
been collected over many years. Climate
helps describe a place or region.

4. Composition of the Atmosphere
17.1 Atmosphere Characteristics
 Major Components
• Air is a mixture of different gases and particles,
each with its own physical properties.

5. Volume of Clean, Dry Air

6. Evolution of Earth’s Atmosphere
• https://youtu.be/ocsV1cA4K4A

7. Composition of the Atmosphere
17.1 Atmosphere Characteristics
 Human Influence
• Emissions from transportation vehicles account
for nearly half the primary pollutants by weight.

8. Height and Structure of the
Atmosphere
17.1 Atmosphere Characteristics
 The atmosphere rapidly thins as you get
higher in altitude.
• Atmospheric pressure is simply the weight of the
air above.
 Pressure Changes

9. Atmospheric Pressure vs. Altitude

10. Layers of the Atmosphere
17.1 Atmosphere Characteristics
 Temperature Changes
• The atmosphere can be divided into four layers
based on temperature.
1. The tropospheretroposphere bottom layer up to 10 Km. Decreasing
temperatures with height.
2. Where all WEATHER occurs. The stratospherestratosphere is from 10-50
Km. Increasing temperatures.
3. The mesospheremesosphere is from 50 to 80 Km. Decreasing temperatures
with height.
4. The thermospherethermosphere is from 80 to 150 Km. Increasing
temperatures due to solar energy.
•

11. Snowy Mountaintops Contrast with
Warmer Snow-Free Lowlands

12. Thermal Structure of the Atmosphere

14. Earth-Sun Relationships
17.1 Atmosphere Characteristics
 Earth’s Motions
• Earth has two principal motions—rotation and
revolution.
 Earth’s Orientation
• Seasonal changes occur because Earth’s
position relative to the sun continually changes
as it travels along its orbit. 23231/21/2
degreedegree tilt on its
axis produces 4 seasons.

15. Tilt of Earth’s Axis

16. Earth-Sun Relationships
17.1 Atmosphere Characteristics
 Solstices and Equinoxes
• The autumnal equinox is the equinox that
occurs on September 22 or 23 in the Northern
Hemisphere.
• The spring equinox is the equinox that occurs
on March 21 or 22 in the Northern Hemisphere.
• Equinox means EQUAL day & night.

17. Earth-Sun Relationships
17.1 Atmosphere Characteristics
 Solstices and Equinoxes
• The summer solstice is the solstice that occurs
on June 21 or 22 in the Northern Hemisphere
and is the “official” first day of summer.
• The winter solstice is the solstice that occurs on
December 21 or 22 in the Northern Hemisphere
and is the “official” first day of winter.

18. Solstices and Equinoxes

19. Energy Transfer as Heat
17.2 Heating the Atmosphere
 Radiation
• Radiation is the transfer of energy (heat) through
space by electromagnetic waves that travel out in all
directions.

20. What Happens to Solar Radiation?
17.2 Heating the Atmosphere
 When radiation strikes an object, there
usually are three different results.
1. Some energy is absorbed by the object.
2. Some radiation travels through substances such
as water and air.
3. Some radiation may bounce off the object
without being absorbed or transmitted.

21. Solar Radiation

22. What Happens to Solar Radiation?
17.2 Heating the Atmosphere
• The greenhouse effectgreenhouse effect is the heating of Earth’s
surface and atmosphere from solar radiation being
absorbed and emitted by the atmosphere, mainly by
water vapor and carbon dioxide.
• An INCONVENIENT TRUTHINCONVENIENT TRUTH.

23. Why Temperatures Vary
17.3 Temperature Controls
 Altitude
• The altitude can greatly influence temperatures
experienced at a specific location. As altitude
goes UP temperature goes DOWN.

24. Mean Monthly Temperatures for
Guayaquil and Quito

26. So how can I find the relative humidity and the dewpoint?
Easy. Just get youself a psychrometer. A psychrometer is just two thermometers.
There’s a ‘dry bulb’
thermometer which just
measures the temperature
of the air in the room.....
and there’s a ‘wet bulb’
thermometer whose bulb
is surrounded by a cotton
wick which is soaked with
water.
Great. So how does
it work?

27. Water evaporates from the wet bulb.
It takes 2260 Joules of heat energy to evaporate
1 gram of water (ESRT pg 1)
That energy comes from the wet bulb itself.
In other words, the evaporating water pulls heat
energy away from the wet bulb leaving it cooler
just the same way you are cooled when
sweat evaporates from your skin.
The more water that evaporates, the cooler the
wet bulb.
So what determines how much water evaporates?
The relative humidity! The drier the air, the
more water evaporates and the more the wet
bulb is cooled.
In other words, the drier the air, the greater the
difference between the dry bulb and the wet bulb!
f the relative humidity was 100% there would be NO evaporation and the
wo thermometers would show the same temperature. No difference.
20o
C
12o
C

28. OK, now what?
Now whip out your reference tables and turn to page 12......
According to our psychrometer (previous slide) the dry bulb is 20o
C and the
wet bulb is 12o
C. Subtract to find the difference. 20 - 12 = 8
Find the dry bulb
temperature (20o
C)
Find the difference
(8o
C)
Now see where
they meet.......
The relative humidity
is 36%. That’s all
there is to it!
OK, but how do you
find the dewpoint?