Temperature is defined as the measure of the warmth or coldness of an object or substance with reference to some standard value.
The temperature of air at any place is influenced by
(i) the latitude of the place;
(ii) the altitude of the place;
(iii) distance from the sea, the airmass circulation;
(iv) the presence of warm and cold ocean currents;
(v) local aspects:
(a) The latitude: The latitude can be explained as an angular distance of a place North or South of the Earth’s Equator or of the Equator of celestial object usually expressed in degrees and minutes. The temperature of a place depends on the insolation received. The insolation varies according to the latitude hence the temperature also varies accordingly.
(b) The altitude: The atmosphere is indirectly heated by terrestrial radiation from below. Therefore, the places near the sea-level record higher temperature than the places situated at higher elevations. In other words, the temperature generally decreases with increasing height. The rate of decrease of temperature with height is termed as the normal lapse rate. It is 6.5°C per 1,000 m.
(c) Distance from the sea: Another factor that influences the temperature is the location of a place with respect to the sea. Compared to land, the sea gets heated slowly and loses heat slowly. Land heats up and cools down quickly. Therefore, the variation in temperature over the sea is less compared to land. The places situated near the sea come under the moderating influence of the sea and land breezes which moderate the temperature.
(d) Air-mass: An air mass is a volume of air defined by its temperature and water vapour content. Air masses may cover many hundreds or thousands of square miles and adapt to the characteristics of the surface below them. Like the land and sea breezes, the passage of air masses also affects the temperature. The places, which come under the influence of warm airmasses experience higher temperature and the places that come under the influence of cold airmasses experience low temperature.
(e) Ocean currents: An ocean current is a seasonal directed movement of seawater generated by forces acting upon this mean flow, such as breaking waves, wind, the Coriolis effect, temperature and salinity differences, while tides are caused by the gravitational pull of the Sun and Moon. the places located on the coast where the warm ocean currents flow record higher temperature than the places located on the coast where the cold currents flow.
