The following are the salient features of the annual range of temperature:-
(1) The annual temperature range is characterized by variations over different parts of the globe. The annual range is lower is low latitudes and higher in high latitudes. In the same latitudes it is higher over the continents and lower over the oceans.
But in the North Pacific Ocean the annual range becomes larger as the distance from the equator increases. In North America and Asia the interior regions are characterised by higher annual range, while the coastal areas have smaller range.
In fact, the magnitude of the annual range of temperature depends on oil the size of the land masses. Because of the vastness of the continent of Asia, Eastern Siberia has as much as 55.6°C of annual temperature range.
Verkhoyansk, situated in the vicinity of the Arctic Circle, is called the cold pole of the earth. The annual range of temperature here is 65° (January – 50°C and July 15°C). This place has the distinction of having a high absolute range of 104.5″C.
(2) Within the tropics, the continental interiors have larger annual ranges than the adjacent oceans. This is evident when the July and January isotherms for the tropical deserts are compared.
(3) In the middle-latitude, at latitude 60° N in Siberia the mean temperature for January is- 34.9°C, while in the same latitude the mean temperature for the same month over the North Atlantic is 4.4°C.
This is a typical example of the effect of differential heating of land and water. The highest values of the annual temperature range are observed in the interior regions of the land areas in temperate zone.
The annual range of temperature over a large segment of the Atlantic Ocean within the Arctic Circle is less than 11°C, while the interior regions of Canada and Siberia have 44.5HC and 66.7°C respectively as their annual ranges.
Winnipeg and Paris, though almost in the same latitude belt, have the annual ranges of 38.9°C and 16°C respectively. This is due to the fact that the prevailing westerly’s bringing in the moderating effect of the Atlantic Ocean to Paris, but Winnipeg is deprived of any such oceanic influence.
(4) In the southern hemisphere, where the land area is limited south of the Tropic of Capricorn, the annual range of temperature over the oceans is only 5.5°C, whereas it is 16.7°C in the continents of South America, South Africa and central Australia. This also shows the effect of oceans on the annual range of temperature.
(5) If we look at the mean temperature distribution maps for the months of January and July in Eurasia in one more characteristic feature of the annual range is clearly discernible: the annual range of temperature increases from west to east on this huge continental land mass.