Diurnal range of Temperature is larger over Land
Diurnal range of air temperature over land is large (as much as 20°C) whereas over sea, it is very small
(less than 1°C), for the following reasons:
| Over Land | Over sea |
| 1. Land, being a solid, has a low value of specific heat and so heats up or cools very quickly. | Sea, being a liquid, has a higher value of specific heat and so heats up or cools slowly. |
| 2. Heat received from the sun is retained by the top layer of land (only a few cm deep) as land is a poor conductor of heat. | Heat received from the sun is distributed over a large mass of water by convection currents. |
| 3. Negligible evaporation | Evaporation of water during day causes adiabatic cooling which balances some of the heat received from the sun. |
The temperature of the land surface, therefore, varies greatly between day and night. Consequently the air in contact with it has a large diurnal range. Since the temperature of the sea surface does not vary much between day and night, the air in contact with it has a practically negligible diurnal range.
Ref : Marine Meteorology By Capt. H Subramaniam
