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Cyclones, hurricanes, tornadoes...

By: Juliana Rocha

Hurricane Floyd*

Hurricane Floyd*

Do you know what cyclones, hurricanes and typhoons are? Or what tornadoes, tropical storms and tropical depressions are? Do you know the difference between a hurricane and a tornado? What about between a tropical storm and a tropical depression?

All these terms refer to climate phenomena. But, wait! Do you know what “climate” is? The ideas of “climate” and “weather” are often used in meteorology, which is the science that studies changes in the atmosphere and interprets data regarding rain, winds, temperature and moisture in the air. When meteorologists talk about “weather”, they are considering short-term changes, such as those taking place within a day or a week. When they talk about climate, on the other hand, they are referring to an average of the changes taking place in the long run (months or years).

The effect of the climate on our lives can be easily understood when we think about the seasons. It’s the position of the Earth in the solar system that determines whether it is summer, spring, fall or winter. However, even though it is summer in Brazil, for instance, not all cities in the country will experience the same temperatures: local conditions, such as lakes, rivers, seas, mountains and the kind of vegetation in the area affect the average behavior of the atmosphere.

Although it is natural for the climate to vary, changes registered in the last 150 years have been a great cause of concern for scientists. The increase in carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) emissions in the atmosphere make it difficult for the planet to cool down, thus producing what came to be called the greenhouse effect, creating new wind patterns and changing the temperature, the rain and the circulation in the oceans. Some of the forecasted consequences of global warming are an increase in sea levels, heavier and more frequent rains, soil erosion and the extinction of animal and plant species.

But that’s another story. Let’s go back to the climate. Each one of the phenomena mentioned at the beginning of the text has a distinct characteristic and is more prone to take place around certain places of the Earth. Tornadoes, for instance, are common around the Rocky Mountains, in the United States. Hurricanes, on the other hand, are witnessed all the time in the Atlantic and in the east and center of the Pacific.

Do you want to know more about hurricanes, tornadoes and storms? So click on the links below to learn more about each one of them.

What are hurricanes?

What are tornadoes?

What are cyclones and tropical storms?

Images:

* September, 7-19, 1999. Category 4. Photo: NASA

See also:

Tropical Cyclone Programme - World Meteorological Organization (TCP/WMO)

National Oceanic and Atmospheric Administration (NOAA)

Hurricane Research Division - Atlantic Oceanographic and Meteorological Laboratory (HRD/AOML/NOAA)

The Online Tornado FAQ - Storm Prediction Center (SPC/NOAA)

NOAA Photo Library

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