Solar radiation reaching the Earth from the Sun is called insolation. Acquisition of solar radiation by the Earth is called the reception of insolation.
So solar radiation coming to the surface is called insolation.
1. Distribution of temperature: The distribution of temperature are is not the same on the entire surface area of earth in context to weather and atmospheric conditions. The following factors are responsible for this unequal distribution of temperature:
2. Distance from the equator: Sun rays fall almost vertically the whole year round on the equator because of which there is more sunlight over there. On the contrary, when we proceed in the direction from the equator towards the poles, the rays of the Sun become tilted. So there is less sunlight there. The temperature on the poles goes even below the freezing point and they always remain covered with snow.
3. Height from sea level: Highest temperature is found at the sea level. The temperature decreases while proceeding upwards from the earth’s surface to a height. Usually, at a height of 165 meters, the temperature drops to 1°C or there is a decline of 6.4°C in temperature for an altitude of 1 km. Shimla has less temperature than Delhi because Shimla is located at a higher altitude than Delhi. Therefore, the mountainous regions are colder than the plains.
4. Distance from the sea: In comparison to land, water takes more time to get heated up and to cool down. Therefore, at places that are near the ocean, the temperature remains almost the same. On the contrary, there is more variation in the temperature of the places located inland, away from the sea.
5. Sea Currents: Sea Currents significantly affect the temperature of coastal areas. In the areas where the hot currents flow, the temperature is high, and in the areas where cold stream flows, the temperature is less. The hot current of ‘Gulf Stream’ maintains high temperatures in the coastal parts of Europe. Thus, sea currents control the temperature of the coastal areas according to their nature.
6. The Prevailing wind: Where the hot winds blow, the temperature is high and when the cold winds blow the temperature is less. The ‘Sirocco’ wind blowing from the Sahara Desert in Italy and the hot winds called ‘Chinook’ blowing in the North American plains, cause an increase in temperature over there. Similarly, due to the Loo blowing in summers in the plains of Northern India, sometime the temperature increases up to 45°C.
7. Slope of Land: The gradient of the surface that comes in front of the sun receives more sunlight, so there is more temperature. On the contrary, on the slopes which are in the opposite direction from the sun, there is less sunlight, and there is also less temperature. The temperature is high on the southern slopes of the Himalayas and Alps, and temperatures is lower on the northern slopes.
8. Nature of the surface: The surface covered with snow and vegetation reflects most of the heat received from the sun. Therefore, the temperature in these regions is not high. On the contrary, the regions covered with sand and black soil absorb most of the insolation due to which the temperature is high over there. The process of reflection of the sun’s heat received by the surface is called ‘Albedo’.
9. Clouds and Rain: Those areas on the land where clouds are present, the rainfall is high. The temperature does not increase as the clouds reflect back the sun’s rays. Like, despite the sun’s rays falling vertical on the cloudy equatorial regions, it does not get as heated up as it gets in the hot desert areas.
