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www.GOALias.blogspot.comDay timeNight timeCoolHotHotCoolFig. 4.11 Land breeze and sea breezespace between the earth and the sun.From the sun the heat comes to us byanother process known as radiation.The transfer of heat by radiation doesnot require any medium. It can takeplace whether a medium is present ornot. When we sit in front of a roomheater, we get heat by this process. Ahot utensil kept away from the flamecools down as it transfers heat to thesurroundings by radiation. Our bodytoo, gives heat to the surroundings andreceives heat from it by radiation.All hot bodies radiate heat. Whenthis heat falls on some object, a part ofit is reflected, a part is absorbed and apart may be transmitted. Thetemperature of the object increases dueto the absorbed part of the heat. Whyare you advised to use an umbrella whenyou go out in the sun?4.54.5 KINDSOF CLOTHESWE WEARINSUMMERAND WINTERYou know that in summer we preferlight-coloured clothes and in winter weusually wear dark-coloured clothes. Whyis it so? Let us find outActivity 4.10Take two identical tin cans. Paint theouter surface of one black and of theother white (Fig. 4.12). Pour equalamounts of water in each and leave themin the mid-day sun for about an hour.Measure the temperature of water inboth the cans. Do you find anydifference in the temperatures? InHEAT4343