Hurricanes need a lot of heat to form, which is why they usually occur over tropical seas (at least 26°C). The sun is close to the equator, providing energy to heat the ocean. The warm ocean heats the air above it causing it to rise rapidly. Water evaporates quickly from the hot surface of the ocean, so the rising air contains great amounts of water vapour. The rising air starts to spin (anti-clockwise in the northern hemisphere)
The centre of the storm – the eye – is calm. As the air rises it cools, condenses and forms towering cumulonimbus clouds. The rapidly rising air creates an area of intense low pressure. The low pressure sucks in air, causing very strong winds. Once the storm moves over land it starts to lose energy and fades.
Answer: The average hurricane moves from east to west due to the tropical trade winds that blow near the equator (where hurricanes start). When a hurricane is still in the Caribbean, the tropical jet blows east to west, and the hurricane moves west to gain power.
What conditions are needed for a tropical storm?
Tropical Storms start within 5º and 30º north and south of the equator where surface sea temperatures reach at least 26.5ºC. The air above the warm sea is heated and rises. This causes low pressure. As the air rises it cools then condenses, forming clouds. The air around the weather system rushes in to fill the gap caused by the rising air.
Why are hurricanes so dangerous?
When hurricanes strike land they can cause huge amounts of damage. Most of the damage is caused by flooding and storm surge. Storm surge is when the ocean level rises at the coastline due to the power of the storm. Hurricanes also cause damage with high speed winds that can blow down trees and damage homes.