Distribution of ocean surface temperature
Topic: Oceans: Hydrological Cycle, Relief of the Ocean Floor, Temperature and Salinity · NCERT: Class 11, Ch 12 "Water (Oceans)"
Meaning
Surface water is warmest near the equator, at about 27°C. It gets colder towards the poles by about 0.5°C for every degree of latitude. It is about 22°C at 20°, about 14°C at 40° and about 0°C near the poles. The hottest water lies slightly north of the equator, along the thermal equator. Northern oceans average about 19°C and southern oceans about 16°C, because northern oceans touch more land. Isotherms are lines joining places of equal temperature. They bend towards the poles along warm currents and towards the equator along cold ones.
Example
In the North Atlantic, the warm Gulf Stream pushes the isotherms far towards the pole. This keeps the sea off western Europe much warmer than other seas at the same latitude.
Don't confuse with
- Vertical distribution of temperature: this is how temperature changes with depth, through the surface layer, the thermocline and the cold deep water. The horizontal distribution is how surface temperature changes with latitude.