Tornadoes are whirlwinds that can grow up to 2.4 kilometres across. They are common in the American Midwest, where warm, moist air from the Gulf of Mexico underlies cold dry air from the north.
Tornadoes form when a long funnel of cloud sinks from a turbulent cumulus cloud. Warm air is sucked upward around the strong downcurrent in a powerful spiral. Wind speeds may reach 600 kilometres per hour lthough no instruments have survived to prove this. Tornadoes can travel up to 500 kilometres without losing much velocity or pressure. Click on the links below to find out more about tornadoes.

Earthquakes are vibrations in the Earth's crust caused by a sudden release of energy from the Earth. They occur when there is a build-up of stress in the Earth's crust, caused by the movement of tectonic plates. The energy released in the form of seismic waves radiate out from the epicentre (surface centre of an earthquakes) The point below the epicentre at which the earthquake actually originates is called the focus or point of origin.

A volcano is a mountain from which hot molten rock and lava, gas, steam, and ash from the inside of the Earth sometimes burst. Romans believed that when Vulcan, their God of Fire, made weapons for the other gods, fire and ash will spew out from the volcano, Vulcano. Greeks believed that Hapaistos, their God of Fire, lived beneath Mount Etna in Sicily. When he beat his red-hot iron, fire will ensue from the volcano above.

• Active volcano: A volcano that erupts year after year.
• Dormant volcano: A volcano that has not erupted for a long time but still shows some signs of activity.
• Extinct volcano: A volcano that has not erupted for hundreds or thousands of years.

Hurricanes are cyclones (rotating vertical columns of air at great speeds) that are generated over the warm tropical oceans and are sustained by winds of over 74 miles per hour (119 kilometres per hour). These devastating cyclones produce and create hazardous winds, torrential rains and extreme flooding, all of which contribute to tremendous damage to property and great loss of life in coastal populations, or wherever the hurricane hits. One such cyclone was Hurricane Andrew, which was single-handedly responsible for causing over 50 deaths and destroying more than $30 billion dollars worth of property. Read on to find out more about hurricanes and their properties.

Many people usually mistake the real meaning of the word “Tsunami”. “Tsunami” is actually a word which means “harbour wave” in Japanese. However, do not be misled by this name – tsunamis usually originate in the ocean. They are usually generated by earthquakes and disturbances underwater, which will then cause a displacement of water and the forming of the massive waves. The effects of Tsunamis can be extremely disastrous, as have been proven by many cases in history. Click on to find out more about Tsunamis.

Flooding is a natural and inevitable process. They usually take place in the event that a river is no longer able to contain all the water that is supplied to it by its sources. Floods take the lives and homes of humans for countless of years. Property damage from floods has risen over the past few years. Therefore, we should learn more about floods, their implications and causes so that we can make decisions which will save lives and reduce property loss.