At the equator, clouds develop as air rises. Clouds frequently bring rain, and the existence of clouds and rain allows tropical rain forests to exist. If the air temperature is less than about 15 degrees C (59 degrees F), water vapor in the rising air will condense into liquid drops that become clouds. As the air cools further, it becomes more dense and falls back to earth as precipitation.
Tropical storms form over the oceans and travel west toward land where they can be strengthened by compression caused by mountains or other topographic features. These storms often produce heavy rainfall and strong winds. Hurricanes are large-scale tropical storms that have sustained wind speeds of at least 74 mph (119 km/h). The strongest hurricanes on record have had wind speeds of 155 mph (250 km/h) or more. Tropical depressions can also intensify into tropical storms or hurricanes if sufficient warm air is present to fuel cloud development or wave action along coastlines may cause tropical depression strength storms to lose their identity as waves break over land instead of in open waters.
Tropical deserts form as a result of low temperatures and high levels of radiation exposure that prevent life from developing. Although deserts cover much of tropical Earth, there are also tropical forests and jungles.
When wet, warm rising air cools and expands in the atmosphere, clouds develop. Water vapor in the air condenses to produce small water droplets, which constitute the foundation of clouds. As the cool air moves upward it becomes less dense than the surrounding hot air, causing it to rise.
Rising air can be either warm or cold. When warm moist air rises it forms clouds. This is known as evaporation cooling. As the moisture in the air evaporates into liquid form it reduces the temperature of the air mass. When the cooled air reaches its saturation point, any additional moisture in the air will begin to fall as precipitation.
When cool dry air rises, it forms clouds too. But instead of reducing the temperature of the air, it increases it. This is known as insolation cooling. The sun's energy is reflected back into space by the earth's surface, but some of this energy is lost due to cloud cover. As long as there is enough cool dry air rising to offset this loss, then more solar energy is converted to heat than with no clouds at all, but since most of this heat is trapped by the atmosphere and not released back to space, we call this a "greenhouse effect".
The atmosphere acts like a giant greenhouse window, allowing sunlight in but also trapping much of this heat inside.
Tropical rainforests are located around the equator owing to the quantity of rainfall and sunshine received in these places. Because of the high temperatures, evaporation occurs at a rapid rate, resulting in frequent showers. The average temperature in tropical forests is 25 degrees Celsius (77 degrees Fahrenheit).
The main reason why you will find most plant life in the tropics near the equator is because it is in the middle of the earth between the two poles. This means that the latitude of the tropics is 0 degrees north or south of the equator. All the planets and the moon's orbit around the earth align so that they are always within the tropics - even during a planet or moon eclipse.
The shape of the earth influences where we will find tropical climates. Since the tropics are on the equator, they are not affected by the polar regions' temperatures. It is only in very extreme conditions that someone might find themselves in a tropical climate far from the equator.
Tropical climates are characterized by warm temperatures throughout the year, with no real seasons. There is much variation in temperature throughout the year in tropical countries, but on average, it is constant at about 30 degrees Celsius (86 degrees Fahrenheit).
The air above the Equator is extremely heated and rises, resulting in a low-pressure zone. Because of this rising air, the Equator receives a lot of rain, resulting in a warm and rainy equatorial environment (e.g., the Amazon and Congo tropical rainforests). This is due to the fact that sinking air does not produce precipitation. The only way for air to sink is by warming up and becoming less dense, which results in evaporation from lakes and oceans and the formation of clouds with high altitude winds that can no longer rise because they are adiabatic (that is, their temperature will never decrease). When these clouds reach their saturation level or become ice crystals, they will begin to fall as precipitation.
As the air cools down at higher altitudes, it becomes more dense and sinks toward the ground. This is why you don't get much rain at high altitudes; there isn't enough hot air being replaced at those levels to produce sufficient wind speed for cloud formation.
The reason the Antarctic doesn't receive much rain is because it sits at the bottom of the world ocean where there is very little surface water vapor in the atmosphere. Since moisture is needed for precipitation, this means that most places on Earth will either receive or lose moisture depending on how close it is to an ocean or large body of water.
Earth's rotation causes differences in pressure across its surface that result in movement of air from high pressure areas to low pressure areas.
The upshot is that you need a way to keep out the heat and moisture from the oceans because it would otherwise destroy all vegetation and any animal that couldn't deal with such conditions would be killed by other organisms more suited to hotter or drier climates.
At the Earth's surface, there are two forces acting on every particle of air: gravity and pressure. At the surface of the Earth, both of these forces are equal in magnitude but opposite in direction. This means that there is no net force acting on the particles of air, and they will stay in place unless acted upon by an external force. In other words, if you don't push or pull something, it won't move.
If you look around you, you'll see that most objects have a weight that pulls them to the ground. This is due to gravity - the same force that keeps the Moon in orbit around the Earth. Without this constant force, the Moon would fly off into space.
But objects also have an upward force due to pressure. This is what allows balloons to rise into the sky.