UNIT 1—LESSON 2
OVERVIEW Describe how the
Earth-Sun relationship affects radiation and incoming solar radiation. Sun Earth Radiation Insolation Radiation (Heat) Balance in the Atmosphere EARTH-SUN RELATIONSHIP
Radiation (Heat) Balance in the Atmosphere
The Sun is a great thermonuclear reactor about 93 million miles from Earth. It is the original source of energy for the atmosphere and life itself. The Sun’s energy is efficiently stored on Earth in such things as oil, coal, and wood. Each of these was produced by some biological means when the Sun acted upon living organisms. Our existence depends on the Sun because without the Sun there would be no warmth on Earth, no plants to feed animal life, and no animal life to feed man.
The Sun is important in meteorology because all natural phenomena can be traced, directly or indirectly, to the energy received from the Sun. Although the Sun radiates its energy in all directions, only a small portion reaches our atmosphere. This relatively small portion of the Sun’s total energy represents a large portion of the heat energy for our Earth. It is of such importance in meteorology that every Aerographer’s Mate should have at least a basic knowledge about the Sun and the effects it has on Earth’s weather.
Learning Objective: Describe how radia-tionand insolation are affected by the Earth-Sun relationship.
The Sun may be regarded as the only source of heat energy that is supplied to Earth’s surface and the atmosphere. All weather and motions in the atmosphere are due to the energy radiated from the Sun.
The Sun’s core has a temperature of 15,000,000°K and a surface temperature of about 6,000°K (10,300°F). The Sun radiates electro-magnetic energy in all directions. However, Earth intercepts only a small fraction of this energy. Most of the electromagnetic energy radiated by the Sun is in the form of light waves. Only a tiny fraction is in the form of heat waves. Even so, better than 99.9 percent of Earth’s heat is derived from the Sun in the form of radiant energy.