RADIATION BALANCE

MET 2101

CLIMATOLOGY

RADIATION BALANCERADIATION BALANCE

What Happensto the SolarBeams?

What Affects Radiation?

VISIBLE

INFRARED

ULTRA VIOLET

UVMuch UV

Absorbed byOzone

SOLAR BEAM IN THE UPPER ATMOSPHERE SOLAR BEAM IN THE UPPER ATMOSPHERE (STRATOSPHERE)(STRATOSPHERE)

VIS

IR

Visible & IR Pass through Ozone with little attenuation

SOLAR BEAM IN THE TROPOSPHERE

The remaining energy goes several places:

Reflected

Sur

fac

e

Reflected Absorbed

Scattered

Clo

ud sAbsorbed

Radiation reaching clouds

Clear Sky Radiation

Solar Radiation Reaching

Troposphere

Dire ctD

iffu

se

Diff

us

e

About 98% of the solar beam passes through the Stratosphere to the Troposphere

On average somewhat more than half passes through clear skies; the rest encounters clouds

The solar radiation is absorbed and scattered by the atmosphere.

It is indirectly reflected by clouds or transmitted to the surface

Radiation scattered by the atmosphere or clouds, but still reaching the surface is called DIFFUSE RADIATION

It hits the surface from all directions

The radiation that passes through without scattering (DIRECT RADIATION) is partially reflected by the surface

Diffuse radiation is not reflected by surface.

Surface Heats Up with Radiation

Thermal IR emitted from heated surface (land & water)

Surface Heats Up with Radiation

Thermal IR increases with daylight

Thermal IR gradually absorbed by clouds and atmosphere

Clouds also reflect part of Thermal IR back down

Radiation Budget in Percent of Solar Input Energy