The correct answer is insolation. The concept of Insolation: • Insolation is the most important factor that influences the distribution of temperature on the earth. • Insolation is the solar radiation that reaches the earth's surface. • It is measured by the amount of solar energy received per square centimeter per minute. • The factor that determines the amount of insolation received is the angle of inclination of the rays. • This depends on the latitude of a place. • The higher the latitude the less is the angle they make with the surface of the earth resulting in slant sun rays. • The area covered by vertical rays is always less than the slant rays. Related Concepts: Solar radiation: • Solar radiation often called the solar resource, is a general term for the electromagnetic radiation emitted by the sun. • Solar radiation can be captured and turned into useful forms of energy, such as heat and electricity, using a variety of technologies. Terrestrial radiation: • It refers to sources of radiation that are in the soil, water, and vegetation. • The major isotopes of concern for terrestrial radiation are potassium, uranium, and the decay products of uranium, such as thorium, radium, and radon. Distance from the sea: • Oceans heat up and cool down much more slowly than land. • This means that coastal locations tend to be cooler in summer and warmer in winter than places inland at the same latitude and altitude.