Module 4: Articles on Natural Disasters

Actually, the term hurricane is used only for the large storms that form over the Atlantic Ocean or eastern Pacific Ocean. The generic, scientific term for these storms, wherever they occur, is tropical cyclone.

The generic, scientific term for these storms, wherever they occur, is tropical cyclone.

Other names they are given, depending on where in the world they are born, are typhoons, cyclones, severe tropical cyclones, or severe cyclonic storms.

As the wind passes over the ocean's surface, water evaporates (turns into water vapor) and rises. As it rises, the water vapor cools, and condenses back into large water droplets, forming large cumulonimbus clouds.

Meteorologists have divided the development of a tropical cyclone into four stages: Tropical disturbance, tropical depression, tropical storm, and full-fledged tropical cyclone.

A pattern develops, with the wind circulating around a center (like water going down a drain).

The winds and the low air pressure also cause a huge mound of ocean water to pile up near the eye of the tropical cyclone, which can cause monster storm surges when all this water reaches land.

However, they often move far inland, dumping many inches of rain and causing lots of wind damage before they die out completely.

Hurricanes do an important job for the Earth. They help move heat from warm tropical places to the cooler temperate zone.

Earthquakes happen when the moving tectonic plates that make up the surface of the Earth move apart or bump into each other, or slide under each other.

The Richter scale (or ML scale) rates earthquakes on an exponential scale, so that if an earthquake is rated 1, you can hardly feel it, but an earthquake rated 2 is ten times as strong as an earthquake rated 1, and an earthquake rated 3 is ten times as strong as an earthquake rated 2.

But sometimes the water pulls all together into a huge wave called a tsunami (tsoo-NAMM-ee).