Solar constant The solar constant is the amount of incoming solar radiation per unit area, measured on the outer surface of Earth's atmosphere, in a plane perpendicular to the rays. Solar constant for Earth, S = 1350 W/m 2
Albedo Albedo is the fraction of sunlight which is reflected off a planet. When an object reflects most of the light that hits it, it looks bright and it has a high albedo. When an object absorbs most of the light that hits it, it looks dark. Dark objects have low albedo..
Earth’s Albedo The average albedo of the Earth is about That means that about a third of the solar energy that gets to Earth is reflected out to space and about two thirds is absorbed
One layer model Assumptions: No atmosphere
Energy Balance P in = P out P in = (1-A) S π R E 2 P out = σ T E 4 4π R E 2 (1-A) S = σ T E 4 4
T earth = 257 K = -16° C = 3.2°F Energy Balance of the One layer model (1-A) S 4 σT4EσT4E Earth’s infrared radiation to spaceSolar radiation Earth
Calculating Surface Temperature of the Earth σ T 4 = S x ( 1- A) 4 Where S - Solar constant σ – Stephan constant x W/m 2 K 4 A - Albedo