Factors affecting ocean temperature
Topic: Oceans: Hydrological Cycle, Relief of the Ocean Floor, Temperature and Salinity · NCERT: Class 11, Ch 12 "Water (Oceans)"
Meaning
Several factors decide how warm ocean water is:
- Latitude: sunlight gets weaker towards the poles, so surface water gets colder.
- Unequal land and water: northern oceans touch more land, so they are warmer.
- Prevailing winds: offshore winds blow from land to sea and push warm surface water away, so cold water rises from below (upwelling). Onshore winds blow from sea to land and pile warm water against the coast.
- Ocean currents: warm currents raise the temperature, and cold currents lower it.
- Enclosed seas: in low latitudes they are warmer than open seas, and in high latitudes they are colder.
Example
Off the coast of Peru in South America, offshore winds cause upwelling, so the sea is cold for its tropical latitude. The Red Sea and Persian Gulf are enclosed and in low latitudes, so they are warmer than the open ocean. The Baltic Sea is enclosed and in high latitudes, so it is colder.
Don't confuse with
- Factors affecting salinity: those are evaporation, rain, river water, and ice freezing or melting. Some factors, such as winds and currents, affect both, but salinity mainly depends on how much fresh water is gained or lost.