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Cyclones

Cyclones, or depressions, are areas of low pressure around which the wind blows counterclockwise in the northern hemisphere and clockwise in the southern hemisphere. The direction of rotation is a direct consequence of the Coriolis Effect, which reflects the rotation of the Earth.

This type of depressions may reach thousands of kilometers in diameter and be as deep as the troposphere (lower layer of the atmosphere, about 10km thick). With a minimum pressure in the center, this phenomenon presents a cyclonic circulation, hence the origin of its name.

There are two types of cyclones: tropical and extratropical. The tropical cyclones, such as hurricanes, are formed in the tropical belt, where they usually move, occurring more frequently in the western part of the tropical regions of the Atlantic and Pacific Oceans, in the northern hemisphere. Extratropical cyclones, though much less violent than tropical cyclones are bigger, last longer, happen more frequently, mainly in the average high latitudes, and affect the weather in much wider areas. Tropical cyclones, potentially more devastating, often cause sensational wind speeds and very heavy rainfall. The word cyclone, as it is, does not necessarily mean the occurrence of a great storm. It rather consists in a common phenomenon (depression) which, in its most intense manifestation, may become devastating (hurricane).

Self-protection Measures

Before:

• Always have at hand a portable radio, an electric flashlight and backup batteries, as well as a first aid kit;
• Help your father to reinforce the roof, doors and windows;
• Warn your parents to clear the drain system around the house;
• Gather all the loose garden equipment and garbage can;
• Tell your parents to anchor the boat or to move it to a safer place;
• Remind your parents to keep the car’s fuel tank full;
• Remind your parents to have an insurance of the house (building and contents).

During:

• Keep calm and try to relax the people that are with you;
• Follow the instructions broadcasted on the radio;
• Stay home, away from windows and doors;
• If you have to leave home, turn off the electricity and close the gas supply;
• Keep away from the areas near the coast, as they can be swept away by the tides;
• Do not go out on a boat;
• If you are not at home, find a shelter immediately.

After:

• After the storm is gone, keep away from the affected areas. Phones should only be used in case of emergency.
• Follow the instructions disclosed by the authorities.