Insolation
Insolation is……
•
•
•
•
IN = incoming
SOL = solar
ATION = radiation
Def: radiation from the sun
We receive only one 2 billionth
(1/2,000,000,000) of all the suns
energy!
• All areas of the Earth
get the same amount
of sunlight!
• Why are some area’s
cold and others hot?
Some area’s have greater intensity
then others
• Intensity of Insolation is correlated to the
average surface temperature.
– As intensity goes up, so does temp.
#1 Factor affecting Insolation
• Angle of Insolation or the angle of the sun
ray’s hitting the earth.
• The greater the angle, the greater the
temperature.
• 00 is cold – 900 is hot
How does angle affect intensity?
What affects angle?
• Time of day
– When is the sun highest in the sky?
– 12 pm, noon
– As the sun gets higher in the sky, what
happens to the shadow length?
– Shadow Video
• Higher angle = small shadow = High
temps
• What determines the angle of insolation
is…
Latitude
• Dictates the angle and duration of insolation (# of
daylight hours)
Date
Latitude
60oN
Angle of
noon sun
6o
Duration of
insolation
5 hrs
Dec 21
Dec 21
40oN
26o
9 hrs
Dec 21
0oN
66o
12 hrs
Intensity due to tilt of the Earth
• The earth is tilted 23 1/2o to the sun which
causes changes in intesity
– Higher latitude = Less intense
– Low latitude = more intense
– Equator is most intense on average.
Why do we experience seasons?
• Seasons are the result of earths tilt and
revolution.
• Tilt = 23.5 degrees, increased tilt = hotter
summers and colder winters.
Seasons are opposite in Southern
Hempisphere
• What if tilt were more/less?
• There would be greater differences in
temperatures for the latitudes.
When does hottest/coldest times of
day/year occur? Why?
Warmest Times
• Temp. rises = incoming energy>outgoing
energy
• Temp. drops = incoming<outgoing
• Radioactive Balance = Incoming energy is
the same as Outgoing energy
• Hottest times occur after maximum
insolation because incoming=outgoing
energy
Greenhouse Effect
• Warming trend due to absorption of
terrestrial (land) radiation (infrared) by
greenhouse gases (CO2 + H2O vapor)
• Without greenhouse gases, the average temp of
59oF, would drop to 0o F
• CH4 (Methane), water vapor, CO2, as well as
Other gases
• If all ice were to melt on Earth seal level would
reach 75m.!
• !
• Seal level is rising 2.5 mm/yr
Sky Dome Model