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Atmospheric Temperature                                 places away from the Equator are colder. This is the
                                                                     reason that Somalia is very hot while Greenland is
            The atmospheric temperature refers to the degree         very cold.
            of hotness or coldness of the air. Temperature we
            feel daily is actually the temperature of the           Aristotle , the ancient Greek philosopher classified
            atmosphere. It is influenced by these factors :         world’s climate into three major zones based on
                                                                    the main latitudes or the distance of a zone from
            Insolation
                                                                    the Equator or the amount of heat received by the
            The incoming solar energy received by the earth is      each zone.
            called insolation . Amount of insolation decreases      Torrid Zone :    The torrid zone receives direct
            from the Equator to the poles. Therefore, places        sunrays, so it is the hottest zone. The zone lies on
            situated close to Equator are hotter than places
                                                                    either side of the Equator upto the Tropic of
            situated close to poles. The insolation is greatest     Cancer in the north and the Tropic of Capricorn in
            when the sun is directly overhead that is around        the south. So, the belt is bounded by the 23½°N
            noon. When the sun is lower in the sky, the same
                                                                    and 23½°S latitudes. The sunrays are almost
            amount of solar energy is spread over a greater         vertical around the year and the region receives
            area of ground surface, so insolation is lower.         maximum insolation. Days and nights are roughly
            Thus, the amount of insolation varies from place
                                                                    of equal length throughout the year.
            to place and from time to time. It also depends on
            the angle of the sunrays.                               Temperate Zone :       The temperate zone lies
                                                                    between the Tropic of Cancer and Arctic Circle in
                                           Insolation
                                                                    the north and between the Tropic of Capricorn
                                                                    and the Antarctic Circle in the south. The
                                                                    temperate zones are neither too hot nor too cold.
                            Reflected by
                            atmosphere                              The sun’s height varies in this zone, so there is a
                                                                    great difference in the length of a day in summer
                    Reflected by
                      clouds                                        and   winter.   The   region   receives   moderate
                                                                    insolation so the temperature also vary in summer
                                                    Absorbed by     and winter.
                                                   the atmosphere
                                                     and clouds     Frigid Zone :   The regions between the Arctic
                                                                    Circle and the North Pole in the Northern
              Reflected by                Absorbed by               Hemisphere and between the Antarctic Circle and
                Surface                     Surface                 the South Pole in Southern Hemisphere are called
                         Mean annual global insolation              the frigid zone. So we have a north frigid zone
            Latitude                                                and a south frigid zone. These zones are the
                                                                    coldest as they receive extremely slanting sunrays.
            The amount of insolation also varies with latitude.     These zones receive the least insolation and
            As we move away from the Equator towards the            experience six months of daylight and six months
            poles, the temperature decreases because of the
                                                                    of darkness.
            variation in the angle of the sunrays. It is believed
            that the poles received about 40% of the total                  Just Think!
            insolation received at the Equator. So there is less
            heat energy available here, with the result that
            these areas are very cold.                               How would you calculate the mean temperature of
                                                                     a place on a certain day?
                 Info Bits
                 Info Bits                                          Distance from the Sea
                                                                    The water heats up and cools down slower than
            As the places near the Equator are hotter and the       the land. During daytime, land gets heated very

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