DAILY INSOLATION OVER THE YEAR AT VARIOUS LATITUDES (NORTH HEMISPHERE)
-
Upload
patricia-snow -
Category
Documents
-
view
217 -
download
1
Transcript of DAILY INSOLATION OVER THE YEAR AT VARIOUS LATITUDES (NORTH HEMISPHERE)
SOLAR DECLINATION (δ): the latitude at which the Sun is directly overhead at solar noon (estimated from the analemma)
-the left axis tells you your declination
-as you follow the analemma, you’ll notice that long dashes indicate the beginning/end of a month
-small dashes indicate a labeled date (e.g. Dec 15)
-once you find the date of interest, look to the left axis for δ
• What would happen if the Earth had no tilt?
• What would happen in Newark if the Earth was tilted 40°?
ELECTROMAGNETIC RADIATION:
• It’s a kind of energy• All objects emit electromagnetic radiation•It’s a collection of waves traveling away from the surface of the objects
Short waves (warmer temperatures)
Long waves (cooler temperatures)
TEMPERATURE
Less energy
More energy
SOLAR AND EARTH RADIATION
In general, the higher the temperature of an object the greater the amount of total energy emitted by that object (Stefan-Boltzman Law)
Earth Temp: 6000 K (5727 C)
Sun Temp: 288 K (15 C)
σ = 5.67 X 10-8 Wm-2K-4
4TE
Solar radiation wavelength range 0.2 – 2.0 micrometers
Shortwave radiation
Tsun= 5798 K ≈ 6000 K
Terrestrial radiation wavelength range 4 – 25 micrometers
Longwave radiation
Tearth = 288 K ≈ 255 K
SOLAR CONSTANT
The amount of solar radiation striking the top of earth’s atmosphere, which is constant (theoretically):
1372 W/m2
SOLAR RADIATION (short wave radiation, SWR)
•As solar radiation passes through the atmosphere, is affected by absoption and reflection
•Absorption: Molecules and particles in the atmosphereintercept and absorb radiation (oxygen and ozone)
•Reflection: Solar radiation passing through the Atmosphere can be reflected
Albedo: An important property of a surface. It measures how much solar energy will be reflected:A surface with high albedo (snow, ice) reflects most of the solar radiationA surface with low albedo (black pavement) absorbs most of incoming solar radiation
INCOMING LWR
LONG WAVE RADIATION (LWR)
•The solar energy is absorbed by the atmosphere, land or ocean and raises the temperature
•The atmosphere, land and ocean also emit energy in the form of long wave radiation
INCOMING LWR
Incoming LWR: Counterradiation
The Earth’s surface emits energy to the atmosphere that is absorbed by the atmosphere and radiated back down to Earth’s surface
R = INPUT – OUTPUTR = ( SWR + LWR) – ( SWR + LWR)
INCOMING LWR
NET RADIATION (RADIATION BUDGET)
It is the difference between total upward and downward radiation fluxes and is a measure of the energy available at the ground surface.