Atmosphere Contents

4. Energy Budgets

Incoming and outgoing energy flows in the Earth's atmosphere are roughly in balance

Energy emitted from the sun is short-wave radiation, while energy emitted from the Earth is long-wave. The solar energy is reflected by the atmosphere, by clouds and from objects on the surface of the Earth. The ratio of radiation reflected and the total radiation acting on a surface is know as the "albedo". The radiation reflected upwards from the surface may be re-reflected or absorbed by clouds and atmospheric impurities. Typical surface albedo values (%) include oceans (10%), forest (5 - 10%), deserts (20 - 40%), field crops 5 - 30%, cities 5 - 20%, ice and snow (75 - 90%) and clouds (50 - 65%).

Nearly half the incoming solar radiation penetrates the clouds and atmospheric gases and is absorbed by the Earth's surface. The energy gained by the surface is balanced not just by radiation loss but by other energy transfers such as conduction and convection (called sensible heat) and the evaporation of water (called latent heat).

What are the main components of the Earth's energy balance?