Imagine a place with no seasons. Where every day seems like the last. A place where it
rains almost every day. A place of constant heat, and humidity.
Some might call such a place a hell, while for others, it might be paradise.
It is a place on earth with more species of plants and animals than anywhere else.
Because of the oxygen generated by its millions of trees, it has been dubbed the lungs of
the world.
You have arrived at the band encircling the centre of the Earth.
Welcome to the Tropical Rainforest.
We begin our journey through Earth’s climate zones here, because here is the very centre
of the Earth, the equator.
And it is no accident that such a hot and wet climate exists on the equator, because
it is here that the sun is strongest, striking the earth directly at 90 degrees. And as it
does so, it causes the hot air to rise, pulling in moisture from the surrounding seas.
As this humid air rises up into the high atmosphere, it cools. But cool air cannot hold onto moisture
like warm air can, and so that moisture precipitates out into vast, towering thunder clouds, which
then finally release as torrential rain.
And it is because of its central position, on the equator, that little to no change in
temperature is experienced throughout the year. While more northerly and southerly latitude
experience the colder and hotter seasons, life on the equator is about watching the
sun drift slightly north and slightly south of being directly overhead. In any position,
it is still beating down, producing that heat, and the thermals that produce all that rain.
There is more complexity to this of course… some areas on the equator experience wet and
dry seasons, but we’ll cover and explain this more in the following video, which concerns
the Tropical Monsoon and Tropical Savannah.
So where in the world can we find these forests? Well, naturally, they’re all within the
tropical zone. The most famous of these is of, course, the Amazon river basin of South
America which stretches across many countries most notably Brazil, Peru, Colombia, Ecuador,
Venezuela and the Guyanas. The Pacific Coast of Colombia on the other side of the Andes
mountains is also home to this climate. And then there’s the Congo basin of Africa mostly
within the country of the Congo Zaire, but also including parts of Uganda. The last of
the three main rainforest zones is in South-East Asia, with almost all of Indonesia and Malaysia
falling within this climate type, along New Guinea and the southern and eastern stretches
of the Philippines. Many islands of the Pacific experience the same climate, including the
Solomon Islands, Fiji and French Polynesia.
So enough chatter – I know you’re all dying to see some temperature and rainfall
graphs, right? Well here they are, across three continents and oceans, all remarkably
the same. High and almost unchanging temperature throughout the year, and high rainfall throughout
the year with no dry seasons.
We should mention something about the graph of Hilo in Hawaii. At almost 20 degrees north
of the equator, it’s pretty far from it, and yet still possesses a very wet and warm
climate. The year-round rainfall is due to it being on the windward side of the large
volcanoes on the Big Island of Hawaii. North-easterly winds, known as trade winds, blow moist warm
air off the Pacific all year round, and when this moist air hits the mountainous slopes,
it rises, cools and dumps huge amounts of rain upon the city.
There are some other parts of the tropics where this pattern is found, including the
Caribbean coasts of Central America and some Caribbean islands, including the Dominican
Republic and Puerto Rico as well as some eastern coastal areas of Brazil and Madagascar. There
will be more on the trade winds in the next couple of episodes – they are key also to
explaining the patterns of wet and dry seasons in other parts of the tropics.
So, what kind of vegetation do we find here? Well… tropical rainforest, funnily enough.
But what is it? Rainforests occur in other parts of the world – forests that grow in
areas of very high rainfall. But the tropical rainforest has a unique combination of high
rainfall and high temperature, which results in the most vigorous plant growth to be found
anywhere on the planet.
This growth most notably occurs in the form of evergreen hardwood trees, meaning dense,
hard wood, like mahogany, teak, sandalwood and rosewood. But unlike the hardwoods of
more temperate latitudes, these trees retain their leaves, and grow, all year round. A
diverse array of plants grow in the shade below the thick tree canopy, and this further
leads to a huge number of animal species in all classes - insects, arachnids, amphibians,
reptiles, birds and mammals. Spend a night in a tent here and… well you’ll soon get
to know some of these guys.
And what about agriculture? Crops that favour the year round rain and high temperatures
include two of the world’s favourites – bananas and coconuts, and they have been farmed commercially
in these regions for a century or more, primarily for export to the developed world. More recently,
the demand for palm oil has increased
considerably, leading to controversial clearing of rainforests, especially in Malaysia and
Indonesia.
Agriculture throughout history, and across the world has always been the principal enemy
of forests. But at this time, with so much global attention on the importance of maintaining
the biodiversity of the tropical rainforests, finding an equitable solution between this
and the economic livelihood of the people that live in these regions seems elusive as ever.
Lastly, we come to major world cities. Are any found in the tropical rainforest? Well
only two feature, and these are just hours apart from each other on the southern tip
of Malaysia. Kuala Lumpur, the capital of Malaysia and famous for the Petronas Towers…
and Singapore, a highly developed global financial, shipping and aviation hub.
So, that’s it for this climate zone. I hope you enjoyed it and I would love to hear your
comments, especially if you live or have experienced personally life in the Tropical Rainforest climate.
As usual, I encourage you all to hit the like button, and Subscribe if you haven’t already
done so, and tell all your friends by Sharing.
I’ll see you all in the next video, as we penetrate the secrets of the Tropical Monsoons
and Savannahs. Until then, stay dry!