1. (Discussion – Atmospheric Heating)
Tuesday April 3, 2018
(Discussion – Atmospheric Heating)

2. What causes weather in Earth’s atmosphere?
The Launch Pad
Tuesday, 4/3/18
1/1
What causes weather in Earth’s atmosphere?
Weather is caused by differential heating of the atmosphere by the Sun.
groundwater

3. Remediation for Quiz 14 begins today and runs through next Monday!
Announcements
Remediation for Quiz 14 begins today and runs through next Monday!

4. Summative or Formative # XC Current Events Crossword
Assignment
Summative or Formative #
Date Issued
Gone Missing Day
Last Day Accepted
XC Current Events Crossword F5
3/29
N/A
Friday, 4/20
QUIZ 14 S2
4/3
Next Monday

5. The Atmosphere Atmospheric Heating

6. terrestrial radiation
Vocabulary
Atmospheric Heating
albedo
scattering
absorption
terrestrial radiation
greenhouse effect
conduction
convection
radiation
absorber
emitter

7. Atmospheric Heating
Heat is the flow of thermal energy, and is always transferred from warmer to cooler objects.
There are three mechanisms of heat transfer:
Conduction through molecular activity.
Convection is mass movement within a substance, usually vertical motions.
Radiation (electromagnetic radiation) travels at a velocity of 186,000 miles per second in a vacuum.

8. Mechanisms of Heat Transfer
Figure 16.17

9. Atmospheric Heating
Radiation (electromagnetic radiation) consists of different wavelengths of energy:
radio waves, microwaves, waves, infrared, visible, ultraviolet (UV), x-rays, gamma (very short waves)

10. Visible light consists of an array of colors we commonly call the “colors of the rainbow.” Rainbows are relatively common optical phenomena produced by the bending of light by drops of water.

11. Atmospheric Heating
Electromagnetic radiation is governed by basic laws.
All objects, at whatever temperature, emit radiation.
Hotter objects radiate more total energy per unit area than do cooler objects.
The hotter the radiating body, the shorter the wavelength of maximum radiation.
Hotter objects emit most of their radiation at shorter wavelengths; hence they will appear to be bluer .
Cooler objects emit most of their radiation at longer wavelengths; hence they will appear to be redder.
Objects that are good absorbers of radiation are good emitters as well.

12. Atmospheric effects include:
Atmospheric Heating
The Earth’s atmosphere is largely transparent to incoming solar radiation.
Atmospheric effects include:
reflection (a surface’s albedo is the percent of solar radiation reflected.)
scattering
absorption
Most visible radiation reaches the Earth’s surface, and about 50% is absorbed at the surface.

13. Average Distribution of Incoming Solar Radiation
Figure 16.20

14. Short wavelengths (blue and violet) of visible light are scattered more effectively than are longer wavelengths (red, orange.) Therefore, when the Sun is overhead and observer can look in any direction and see predominately blue light that was selectively scattered by the gases in the atmosphere. By contrast, at sunset, the path that light must take through the atmosphere is much longer. Consequently, most of the blue light is scattered before it reaches the observer. Thus, the Sun appears reddish in color.

15. The lower atmosphere is thereby heated from Earth’s surface.
Atmospheric Heating
Earth re-radiates radiation (terrestrial radiation) at the longer wavelengths.
Longer wavelength terrestrial radiation is absorbed by carbon dioxide and water vapor in the atmosphere.
The lower atmosphere is thereby heated from Earth’s surface.
Heating of the atmosphere in this manner is termed the greenhouse effect.

16. The Heating of the Atmosphere

17. Temperature Measurement
The most common temperature measurement of our atmosphere is daily maximum and minimum.
Other temperature measurements include:
daily mean temperature
daily range
monthly mean
annual mean
annual temperature range

18. Mean monthly temperatures for two locations in Canada
Mean monthly temperatures for two coastal locations
Figure 16.27

19. Temperature Measurement
From a human perspective, anything that influences the rate of heat loss from the body also influences the sensation of temperature.
Important factors for human perception of temperature are:
air temperature
relative humidity
wind speed
sunshine

20. Controls of Temperature
Temperature variations are controlled by several factors:
Receipt of solar radiation is the most important control.
Another important control of temperature variation is differential heating of land and water.
Land heats more rapidly than water, so land gets hotter than water, cools faster than water, therefore land can also get cooler than water.

21. Controls of Temperature
Temperature variations are controlled by several factors:
Other important controls of temperature variation include:
altitude
geographic position
cloud cover
albedo