GEO 101, Feb 4, 2014
Finish isolines
Atmosphere intro
Freezing rain is supercooled
liquid water
Variation in incoming solar radiation
Graupel is
white because
it has air
trapped inside
Sleet is more
colorless
Sleet: frozen raindrops that bounce on impact with
the ground
Quantitative means the THEME has VALUES
Daily Average Solar Radiation
Isolines: lines that connect points of equal value and
enclose areas of equal value.
Isoline interval: difference between value of successive
isolines
30
20
10
1
Isolines that show elevation are contour lines
Isolines that show elevation are contour lines
Isolines that show elevation are contour lines
Match the map to the shape
1
80
60
40
20
2
0
4
A
3
5
6
B
C
Isolines for GEO 101
Precipitation : isohyets
D
Temperature : isotherms
E
F
Atmospheric pressure : isobars
Isoline rules:
Isoline rules:
1. All locations on a given isoline have the same value
3. Widely spaced isolines represent gradual changes in
values
2. Closed isolines represent a high or a low set of values
4. Closely spaced isolines represent abrupt changes in
values
Everything inside is
less than 20
20
10
20
30
2
Isoline rules:
5. All isolines eventually close either on or off the map
Draw in 150”,
100”, & 50”
isohyets
6. Isolines never cross one another
7. Isolines never split or have branches
500
Atmosphere: blanket of air surrounding earth
1. Insulator
2. Shield (meteors, ultraviolet radiation)
3. Enables travel of sound waves, aircraft
Dynamic: currents and circulation cells
Atmosphere important in equalizing temperature
and pressure by transfer of heat, energy, and
moisture around world
400
Air molecules
Altitude (km)
Without our atmosphere: cold, quiet, cratered place
312 mi
300
200
Air density
100
62 mi
Air
pressure
Layers of the
atmosphere based on
“temperature”
90% in first
10 mi
10 mi
Meteorology...the study of weather
condition of atmosphere at a given time for a given area
Little info.
Stratosphere
It gets colder as you
go up in the
troposphere because
you get farther from
the earth, the main
heat source.
temperature, pressure, wind, moisture
Climatology...the study of long term average weather
usually over past 30 years
Tropopause
Troposphere
We live in the troposphere
3
Driving force behind weather and climate
How bright the sun shines
Factors affecting intensity
1. Angle of the sun’s rays
Total insolation is a function of
intensity x duration
Primarily related to latitude
1. Angle of the sun’s rays affects intensity of insolation
Latitudinal comparison
Angle of
incidence
Surface area
covered
How bright the sun shines
Factors affecting intensity
1. Angle of the sun’s rays
2. Atmospheric transparency (clouds, etc.)
(Latitude and season affect angle of sun’s rays)
2. Atmospheric transparency affects intensity of insolation
Clouds
Air pollution
Smoke
Volcanic ash: Chile, 1993
Dust storm approaching Stratford, Texas. Image ID: theb1365, Historic
C&GS Collection, April 18, 1935, Credit: NOAA George E. Marsh Album
4
100% at top of
atmosphere
How bright the sun shines
5% scattered
or reflected
30-60% reflected by
clouds
Factors affecting intensity
1. Angle of the sun’s rays
15% absorbed
by molecules
and dust
2. Atmospheric transparency
3. Altitude
80% can reach
ground on
clear day
5-20% absorbed
by clouds
0-45% reaches ground
on cloudy day
500
400
312 mi
The higher up you are, the fewer air
molecules are between you and the sun
3. Altitude affects intensity of insolation
Mt. Everest, 5.5 mi high
Altitude (km)
Air molecules
300
200
Air density
100
62 mi
Air
pressure
90% in first
10 mi
10 mi
March Equinox
How long the sun shines during the day
Depends on latitude and season
December
Solstice
June
Solstice
Sept. Equinox
5
http://www.youtube.com/watch?v=ndlQNicOeso
Approximate Duration of Insolation
Arctic “midnight sun”
Spring June
Fall
December
Equinox Solstice Equinox Solstice
N.Pole
12 hrs.
24 hrs.
12 hrs.
0 hrs.
N.Mid-Lat
12 hrs.
~16 hrs
12 hrs.
~8 hrs.
Equator
12 hrs.
12 hrs.
12 hrs.
12 hrs.
S.Mid-lat
12 hrs.
~8 hrs.
12 hrs.
~16 hrs
S. Pole
12 hrs.
0 hrs.
12 hrs.
24 hrs.
High-latitudes, low angle sun
Range in elevation of noon sun
Equator: 90° to 66.5°
Mid-latitudes: sun never
directly overhead
23.5
Tropics: sun is directly
overhead once or twice a year
Low latitudes
23.5
66.5
Mid-latitudes: sun never
directly overhead
High-latitudes, low angle sun
N
Range in elevation of noon sun
Equinoxes
Equinoxes
66.5
S
Horizon
Range in elevation of noon sun
Tropic of Cancer: 90° to 43°
Mobile = 30.5ºN
Mobile: 83° to 36°
23.5
Tropic of Cancer = 23.5ºN
Difference = 7
7
June
23.5
23.5
23.5
43
36
N
Horizon
S
N
Horizon
S
6
Range in elevation of noon sun
Anchorage, AK: 52.5° to 5.5 °
Range in elevation of noon sun
North Pole: 23.5° to 0°
Anchorage = 61ºN
North Pole = 90ºN
Tropic of Cancer = 23.5ºN
Difference = 37.5
Tropic of Cancer = 23.5ºN
Difference = 66.5
37.5
66.5
23.5
Can you
look north?
23.5
N
Horizon
5.5
What is the “top of the
atmosphere” ?
TROPICS: insolation high year round
due to high sun angle and ~ constant
duration
Mid-latitudes: insolation highest at
summer solstice due to higher sun angle
and longer day, lowest at winter solstice
due to low angle and short day
23.5
S
N
Equinoxes
Horizon
S
Seasonal variation in insolation at top of atmosphere
Equator
Poles
Duration
Angle
Total
Spring
Equinox
12 hrs.
High
Sum.
Solstice
12 hrs.
High- High- 24 hrs
Low
Fall
Equinox
12 hrs.
High
12 hrs.
Horizon Low
Winter
Solstice
12 hrs.
High- High-
0 hrs.
Below
Zero
horizon
High
High
Duration Angle
12 hrs.
Total
Horizon Low
High
Total annual insolation decreases as latitude
increases
Seasonality (difference between winter and
summer) increases as latitude increases
Poles: insolation highest at summer
solstice due to 24 hour duration low angle
sun, none at winter solstice
7
Insolation on the June Solstice
Comparison between top of atmosphere and Earth surface
Global average annual energy balance
Duration factor
23.5°N
Surplus
Top of atmosphere
Mid-High latitudes
N. Pole
Equator
Deficit
Tropics
San Francisco
St. Louis
Washington DC
90°N
80°N
0
4
8
12
16
20
24
28
32
36
40
60°N
At top of the atmosphere
50°N
40°N
30°N
20°N
10°N
00°N
10°S
20°S
Megajoules/m2/day
Chart monthly insolation at the Equator
70°N
90° sun
elevation
30°S
40°S
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
50°S
35
60°S
44
70°S
37
38
37
34
33
34
36
38
37
36
36
80°S
90°S
48
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Chart of monthly insolation at the Equator
Chart monthly insolation at the North Pole
50
45
4
40
8
12
35
44
20
24
28
16
32
36
20
24
8
12
16
40
36
32
28
30
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
25
0
20
0
0
20
39
44
40
24
1
0
0
0
15
10
5
Jan Feb Mar
Apr May Jun
Jul
Aug Sep Oct
Nov Dec
8
50
Chart of monthly insolation at the North Pole
(dark bars = N.P., light are Equator for reference)
Chart monthly insolation at the South Pole
45
40
40
35
32
36
30
24
28 20
16
16
12
12
24
32
20 28
40
36
44
25
44
20
15
10
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
5
44
Jan Feb Mar
Apr May Jun
Jul
Aug Sep Oct
25
6
0
0
0
0
0
0
17
37
49
Nov Dec
Example only, do not use your sheet for this demo. problem.
Class assignment: if your last name begins with
90° S
A-B, do 80°N and 10°S
C-D, do 70°N and 20°S
E-H, do 60°N and 30°S
I-L, do 50°N and 40°S
M, do 40°N and 50°S
N-Q, do 30°N and 60°S
R-T, do 20°N and 70°S
U-Z, do 10°N and 80°S
9