Black Body Radiation and the Earth

A perfect black body

is an object that absorbs all of the radiation that hits it. No radiation is reflected or transmitted.

Perfect black bodies are also

best emitters

What does temperature determine?

intensity and distribution of wavelengths

The higher the temperature

the higher the intensity of each wavelength

Intensity

power per unit area

What does a higher intensity mean?

More power

More energy per second

So overall more energy

Intensity increases more rapidly

for shorter wavelengths than for longer wavelengths

so peak wavelength decreases

Process of Earth’s constant temperature using radiation

At daytime, the Earth receives and absorbs lots of radiation

so temperature increase

At night, more radiation is emitted than absorbed

so temperatures decrease

If its is cloudy

It is cooler since more radiation is reflected by clouds