Energy from the sun

 We may notice that it is very hot in some months and very cool in other months. This is variation of temperature in one place. Temperature also varies from one place to another on the earth. Some regions are warm while some regions are cold and covered with ice throughout the year. 

Solar Energy and Sun's rays

 The sun is the principal source of energy on earth's surface. It is like powerhouse which generates and gives an energy in the form of light and heat. The energy which is constantly emitted by the sun is known as radiations. When a body gives out the energy, it is called radiation. The other forms of energy from the sun are UV rays, radiowaves, x-rays which we neither feel.or see.

       The solar radiation received on the surface of earth is called 'insolation'. The actual amount  of solar energy recieved on the ground level is only a small portion of what reaches the earth's atmosphere. This is because about one third of solar energy is reflected back by the earth's atmosphere. Further, some portion of rays is scattered and absorbed by the atmosphere. In fact some harmful rays like UV rays don't reach on the earth this made life possible on earth.

Some amount of sun rays is absorbed and reflected by clouds and smoke.

    

   

   

As we can see sun rays fall at about 90° on the equator, they fall slantingly towards the Poles. This is called 'Angle of Incidence'. 

       Even though more intense of sun rays fall on Equatorial region, it is usually cloudy there after midday and less sun rays fall on the ground . As the earth goes around the sun in course of year, the angles of Incidence' change constantly change. Thus angle of incidence increases in the north during months of November and December and decreases in months of May, June. 

Land and water Constrats

   The temperature distribution over land and oceans are quite different and varying. The temperature of different places over different continents are different. Land is considered as a good conductor of heat, whereas water bodies are different. While land takes heated and cooled quickly, oceans will take time to heat and cool. 

     

    

  Heat balance

     The heat, the earth recieves is radiated back in different ways. The entire heat is not radiated back, then every day the amount of heat that remains will accumulate and it will become hotter and hotter. On the other hand, if the earth recieved less heat than it become cooler and cooler.

         Some gases like carbon dioxide prevent radiation of heat from the earth. Carbon dioxide in atmosphere increases due to use of petrol and diesel, cutting down forest etc. If the carbon dioxide proportion in the atmosphere, less heat will be radiated and it causes 'Global warming'.

    

High and Low temperatures

  Scientists has recorded the highest and lowest temperature reached on the earth. The highest temperature is from place called Azizia in Libya(Africa) where in July 1922 the temperature reached 57.7°c Coldest temperature is at Vostok Station of Antarctica, the temperature fell to -89°c in July 1983.