Stages and parts of hurricanes

Tropical Depression — Tropical Storm — Hurricane

Hurricanes can often live for a long period of time — as much as two to three weeks. They may initiate as a cluster of thunderstorms over the tropical ocean waters. Once a disturbance has become a tropical depression, the amount of time it takes to achieve the next stage, tropical storm, can take as little as half a day to as much as a couple of days. It may not happen at all. The same may occur for the amount of time a tropical storm needs to intensify into a hurricane. Atmospheric and oceanic conditions play major roles in determining these events.

Hurricanes

As surface pressures continue to drop, a tropical storm becomes a hurricane when sustained wind speeds reach 64 knots (74 mph). A pronounced rotation develops around the central core. Hurricanes are Earth’s strongest tropical cyclones. A distinctive feature seen on many hurricanes and are unique to them is the dark spot found in the middle of the hurricane. This is called the eye. Surrounding the eye is the region of most intense winds and rainfall called the eye wall. Large bands of clouds and precipitation spiral from the eye wall and are thus called spiral rain bands.

Hurricanes are easily spotted from the previous features as well as a pronounced rotation around the eye in satellite or radar animations. Hurricanes are also rated according to their wind speed on the Saffir-Simpson scale. This scale ranges from categories one to five, with five being the most devastating. Under the right atmospheric conditions, hurricanes can sustain themselves for as long as a couple of weeks.

Upon reaching cooler water or land, hurricanes rapidly lose intensity.

Parts of a Hurricane

When a tropical storm forms into a hurricane, it is divided up into many different parts. These parts include the eye, the eye wall, and the spiral bands.

The Eye: The eye of a hurricane is the calmest area of the tropical cyclone. The rest of the hurricane revolves around the eye (the centre). The size of the eye can range from 20 to 50 kilometres in diameter. It is described as a dark grey empty hole with fierce winds and rain surrounding it. It is so calm that it has the lowest reading ever recorded on a barometer, so that the fierce winds can’t even reach the centre. Often people mistake that the hurricane is over, because one side has passed, but most of them don’t know that the other half of the hurricane is still on its way. Scientists often fly planes into the eye of a hurricane to measure how deadly a hurricane is going to be.

The Eye Wall: Many agree that the most deadly area of a hurricane is the eye wall. The eye wall is literally a wall of clouds that surround the eye. It is very odd that the most deadly area surrounds the calmest area. The eye wall actually creates the eye by sucking out any clouds or rain in the area. The eye wall can produce wind speeds over 155 miles per hour. This occurs because winds within the eye wall converge, creating havoc wherever it hits. The spiralling winds shoot warm air up through the hurricane, which releases heat as an energy source for the hurricane. The air shooting up also causes extreme winds and a lot of rain. So while creating damage by itself, it acts like an energy source for other parts of the hurricane.

Spiral Bands: The spiral bands are thin clouds that surround the eye wall. This is the largest area of a hurricane, and where most of the rain falls. In many situations, the spiral bands can let out one foot of rain every day. This rain causes flooding in most cases. The spiral bands produce fierce winds, although not nearly as fierce as the “eye” winds.