Lecture 4, Chapter 3: Earth’s Modern Atmosphere
Layers of the Atmosphere
1. ________________(50-300 miles)
2. ________________ (31-50 miles)
3. ________________ (11-31 miles)
4. ________________ (0-11 miles)
Each layer is separated by a “_____________” (meaning to change).
1. Thermosphere
Traits:
; The ___________ layer of the atmosphere, from 50-300 miles. Its upper boundary is called the
______________. Beyond that is the ______________.
; ________________ occur in the thermosphere
; Temperatures _______________ in the thermosphere, up to 2200 degrees F. ; This is because there is intense radiation that makes the nitrogen and oxygen vibrate a lot and the
amount of vibration is what determines “temperature”. But it doesn’t feel hot. This is because,
although the individual molecules are moving rapidly, there are hardly any molecules. So, the
energy can’t transmit from one molecule to another.
; __________________occur here.
2. Mesosphere
Traits:
; Occurs from ______________ above the earth’s surface.
; Its upper boundary is the ________________________
; It is the ____________________ of the atmosphere: molecules aren’t moving as much as they
are in the layers above and below it.
; Fine ice crystals form on dust, creating _______________________. ; The ionosphere is here (and in the thermosphere). It absorbs _____________________.
3. Stratosphere
Traits:
1. From _____________ miles.
2. Boundary is the _________________________
3. Temperatures keep ___________________ with altitude in the stratosphere because:
4. The _________________ is in the stratosphere. Ozone (O) is made up of _________ oxygen atoms (instead of the usual 2 atoms that make up oxygen 3
gas).
The ozone layer absorbs ______% of UVC (ultraviolet C) rays coming from the sun, and _______of the
UVB (ultraviolet B) rays. Most (98%) of the ultraviolet rays that make it to the earth are __________
rays).
Matching:
A. Thermosphere
B. Mesosphere
C. Stratosphere
1. Uppermost layer
2. Coldest layer
3. Contains the ozone layer
4. Auroras occur here
5. Noctilucent clouds occur here.
6. Ionosphere occurs here (2 answers)
7. Temperatures rise sharply (up to 2200 degrees F)
What is NOT true of the Thermosphere?
A. Temperatures rise rapidly, up to 2200 degrees F.
B. The ionosphere is here
C. Noctilucent clouds occur here
D. The exosphere occurs beyond the thermopause
E. Auroras occur here
F. The ionosphere is here. It absorbs gamma and x-rays.
G. Above the thermopause (300 miles above ground) is the exosphere – outer space.
The Ozone “Hole”
thUntil the 20 century, ozone levels had been ___________________________ for several hundred
million years. Now it is in a state of ____________________.
The ozone layer is thinning, particularly in the upper latitudes. This thinning is called a “hole” although
it isn’t a total hole.
The hole is caused by chlorine atoms that decompose ozone. These atoms are coming from CFC’s, which are _________________________that were widely used in __________________,
__________________________.
They migrate into the stratosphere, where UV radiation splits them, freeing chlorine atoms. The chlorine can destroy ozone, turning it into oxygen gas.
Why the ozone holes are over the Poles
CFCs from the Northern Hemisphere end up concentrated over the South Pole for two reasons:
1. During the long cold winter months, ____________________ forms over Antarctica. It doesn’t
mix much with the lower atmosphere, and chemical reactions are enhanced in this enclosed air
mass. (Over the North Pole, conditions are more changeable, so the hole is smaller).
2. ________________clouds in the stratosphere (especially those with nitrogen oxide in them) over
the Poles help catalyze the release of chlorine.
The Banning of CFCs
Chemical manufacturers claimed that CFC’s were not harming the ozone layer, and delayed action for 15 years. But finally a Montreal Protocol was adopted in 1987 banning CFCs.
Are CFC’s are still being produced?
How many oxygen molecules does ozone have?
A. 1
B. 2
C. 3
D. 4
T/F The ozone layer absorbs 75% of the UVC (ultraviolet C) rays
T/F The ozone layer absorbs 100% of the UVB (ultraviolet B) rays.
T/F Most of the ultraviolet rays that make it to the earth are UVA (ultraviolet A rays).
thT/F Until the 20 century, the ozone layer had been relatively stable
Which was most responsible for thinning the ozone layer?
A. Methane
B. Carbon dioxide
C. Carbon monoxide
D. CFC’s
Which is TRUE?
A. The ozone layer is the thinnest in the mid-latitudes
B. The polar vortex and polar stratospheric clouds help make the ozone layer thinnest over the poles.
C. The attempt to ban CFC’s was tried, but an international treaty was never signed.
D. There was once an ozone “hole” but it is now completely healed.
3. The Troposhere
Traits:
; At 0 to 11 miles, it is the __________ (closest to earth) layer of the atmosphere: the one where
we live.
; It contains 90% of the total mass of the atmosphere: the bulk of all :
; The ________________ is the troposphere’s upper limit. Its height varies over time and place.
; Temperatures _______________ with increasing altitude.
Which is NOT true about the troposphere?
A. Lowest (closest to earth) layer of the atmosphere: the one where we live.
B. 90% of the total mass of the atmosphere: bulk of all water vapor, clouds, and air pollution.
C. The tropopause is the troposphere’s upper limit. Its height varies over time and place.
D. Temperatures increase rapidly with increasing altitude.
Normal lapse rate:
Environmental lapse rate:
T/F The environmental lapse rate is the average rate of decrease in temperature. It is 3.5 degrees F per 1000 ft.
On Your Own:
Look at Figure 3.3, page 64 in the text. Where was Kittinger’s ballon: the troposphere, stratosphere,
mesosphere, or thermosphere?
Look at Figure 3.7, page 69 in the text:
Where do the gamma rays get stopped on their path towards earth? At beyond 500 miles, 50-300 miles, 31-50 miles, or 11-50 miles?
Where do X-rays get stopped on their path towards earth? At beyond 500 miles, 50-300 miles, 31-50 miles, or 11-50 miles?