Horizontal Distribution of Temperature in Oceans

  • On an average, the temperature of surface water of the oceans is 26.7°C (80°F) and the temperature gradually decreases from equator towards the poles.

Horizontal distribution of temperature of ocean water

 

  • The rate of decrease of temperature with increasing latitudes is generally 0.5°F per latitude.
  • The average temperatures become 22°C (73°F) at 20° latitude, 14°C (57°F) at 40° latitude, and 0°C (32°F) near the poles.
  • The oceans in the northern hemisphere record rela­tively higher average temperature than in the southern hemisphere.
  • The highest temperature is not recorded at the equator rather it is a bit north of it. The average annual temperature of all the oceans is 17.2°C (63°F).
  • The average annual temperatures for the northern and southern hemispheres are 19.4°C (67°F) and 16.1°C (61°F) respectively.
  • The variation of temperatures in the northern and southern hemispheres is because of unequal distribution of land and ocean water.
  • The decrease of temperature with increasing latitudes in the northern Atlantic Ocean (figs. below) is very low because of warm ocean currents.

Horizontal distribution of temperature of Atlantic Ocean Water

 

  • The average temperature between 50°-70°N latitudes is recorded as 5°C (41°F). The decrease of temperature with increasing latitudes is more pronounced in the southern Atlantic Ocean.
  • The highest temperature of surface water of the oceans is at 5°N latitude whereas the lowest temperature is re­corded between 80°N and the north pole and between 75°S and the south pole.
  • The average annual tempera­ture of the Pacific Ocean is slightly higher than the Atlantic Ocean (16.91 °C or 60°F) and the Indian Ocean (17°C or 60.6°F).
  • The lowest (3.3°C or 35.94°F) and the highest (32.2°C or 89.96°F) temperatures of the oceans are recorded near New Scotland and in the western Pacific Ocean respectively.
  • The highest tem­perature of the Indian ocean (25°C or 82.4°F) is re­corded in the Arabian Sea and Bay of Bengal but the enclosed seas of the Indian Ocean record still higher temperatures (Red Sea = 32.2°C or 90°F and Persian Gulf = 34.4°C or 94°F).
  • The average seasonal tempera­tures (February and August) of surface water of the oceans have been represented through isotherms .

 

Horizontal Distribution of Temperature of Indian Ocean Water

 

  • The temperature of the surface water of the oceans is higher than the air temperature above the ocean surface which means ocean surface gives off heat to the atmosphere.
  • This phenomenon influences the generation of oceanic circulation mainly sea waves and ocean currents.
  • It has been observed that the air temperature at the height of 8m from the sea surface between 20°N and 55°S latitudes in the Atlantic Ocean is cooler by 0.80°C than the sea surface.
  • There is a lot of variation in the heat emitted from the oceans to the atmosphere during winter and summer and this phe­nomenon causes differences of air temperature over the oceans and the continents mainly during winter season.
  • The temperature for January is 22.2°C higher over the oceans between 20° and 80°N, while in July it is 4.8°C lower.
  • The mean annual temperature is 7°C higher over the water meridian’.
  • The difference between air and sea surface tempera­tures causes fogs over the seas and the oceans.
  • This happens when warm air passes over a cold sea surface having the temperature below dew point of the air.
  • Consequently the air over the sea surface is cooled from below and sea fog occurs.
  • Generally, sea fogs are frequently formed during spring and early summer because air coming from over the land is warmer while the sea surface is still cold.
  • Sea fogs are very common in the high latitudes but are generally absent in the tropics.