The following factors affect the horizontal distribution of temperature.
1. Latitude: As a general rule, temperature decreases from the equator to the poles. Because, the sunrays fall more oblique as we go north or south of the equator. The oblique rays spread on a bigger area than the perpendicular rays and also pass thicker layers of the atmosphere where their heat is absorbed by water-vapour, dust particles and carbon dioxide.
2. Land-water contrasts: It is another important factor affecting the horizontal distribution of temperature. The land gets heated and cooled down more rapidly than the sea. Thus, the contrast between land-sea temperature effect the horizontal distribution of temperature and Isotherms take sudden bends at land-water edges.
3. Ocean currents: The ocean currents also have great influences on the horizontal distribution of temperature. The warm currents increase the temperature while cold currents reduce it in the coastal regions.
4. Winds: Cold and warm winds also affect the horizontal distribution of temperature. Warm winds increase the temperature whereas the cold winds decrease it.
5. Relief and altitude: Relief features such as plains, mountains and plateaus control the temperature by way of modifying its distribution. As we move upwards from sea level we experience a gradual decrease in temperature.
6. Vegetation cover: Vegetation cover absorbs much of the sun's heat and prevents quick radiation from the earth whereas the soil receives more rapidly. For example, the annual range of temperature in the equatorial region is 5°C while it is 38°C in the desert.
7. Nature of the soil: Colour, texture and structure of soil modify temperature to a great degree. Black, yellow and clay soil absorb more heat than sandy soil.
8. Slope and aspect: Angle of the slope and its direction control the receipt of insolation. South facing slopes are warmer than north. The northern slopes are exposed to cold winds. The slopes get oblique rays of sun.
