Rain forest are forest with heavy annual rainfall. I always see the rainforests on Discovery or Natgeo tv channel. And, I was wondering why does it rain so frequently in the rainforests?
Rainforests covers less than 2 percent of the Earth’s total surface area, the world’s rainforests are home to 50 percent of the Earth’s plants and animals. Evergreen forest get an annual rainfall of at least 406 centimeter. Rainforests are found on every continent across the Earth, except Antarctica.
- Receive >1500 mm of rainfall each year
- Rainfall relatively evenly distributed throughout the year, >100 mm/month
- Evergreen trees
- Relatively little change in temperature throughout year
- High humidity
[ Photo Credit: Early morning misty view of the forest of East Kalimantan, Indonesia, Borneo Photo © Mark Godfrey/TNC ]
So why does it rain so frequently in the rainforests?
After searching for couple of hours, I finally found the answer to my question –
- Solar radiation is strongest near the equator
- The equator is mostly covered by water so a large amount of water evaporates
- As air heats it become less dense and rises
- As air rises it cools and water condenses to form rain which is why the tropics are wet
- Air flows from high pressure to low pressure areas
- Hadley cell – system of air and water vapor circulation near the equator
- Intertropical convergence zone (ITCZ) – convergence of northern and southern Hadley cells, moves from 23N to 23S with the change in season
- Rain forests fall within boundaries of ITCZ
- Spinning of the earth (Coriolis effect) means that Hadley cells are actually curved
- In areas where there are mountains near the coast and prevailing winds are towards the continent, water evaporates from the ocean, as it rises over the mountains it cools and water condenses to form rain – this is the reason for most temperate rain forests
Now I’m feeling little satisfied :)