Hurricane Matthew seen from ISS (NASA)Hurricane Matthew, a strong tropical cyclone, is travelling north along the southeastern coast of the US. It is a Category 5 hurricane, the most powerful on the scale. Matthew formed off the African coast on 22nd September, travelling westwards until it developed into a tropical storm just off the Leeward Islands (on the eastern edge of the Caribbean Sea) on 28th, and then a full-scale hurricane the following day. Rapidly gaining strength all the time, the storm's path took it past Haiti, Jamaica, Cuba, Dominican Republic and The Bahamas. It reached Florida on the morning of 7th October, and is expected to move on to Georgia, South Carolina and North Carolina, driving storm surges and heavy rain inland as it goes. Winds gusting at more than 120 mph are bringing down power lines, causing power losses. It is expected to curl out into the Atlantic Ocean on Sunday 9th.
Hurricane Matthew moves north to Florida (NASA)
Route of Hurricane Matthew (NASA)Evacuation orders have been issued for millions of people in major cities such as Jacksonville, Florida and Savannah, Georgia. President Barack Obama has declared emergencies in Florida, Georgia and South Carolina, promising federal aid. Highways were jammed with people streaming inland to escape the storm. People flocked to stores to stock up on food, water and other essentials.
Flooded street in Haiti (Thomson Reuters)Haiti was cut in half after Matthew hit on Tuesday 4th October, with all routes to the south of the country, which has been devastated by the hurricane, blocked by flooding. Roads, bridges and communication lines were swept away. Floodwaters bring the threat of waterborne diseases, such as cholera, and many people have been left without shelter, food and fresh water. Around 900 people have been reported dead.
Hurricanes begin as warm, moist air is heated by the Sun and rises high into the atmosphere over the tropical Atlantic, Indian and Pacific oceans. The rising air sucks in more air, which begins to swirl around in a spiral. The moisture in the rising air condenses into clouds. Quickly the hurricane balloons in size and the swirling winds reach 250 km/h (400 mph). The spirals of deep cumulonimbus clouds unleash massive downpours, bringing up to half a year’s average rainfall in a few hours.
Diagram of a hurricane
The hurricane moves along quite slowly, around 25 km/h (15 mph), as warmed air rises and swirls most powerfully near its centre. Most spills out at the top and is flung to the edges where it sinks. A small portion drifts down at the centre or “eye” of the storm. This is usually 25–40 kilometres (15–25 miles) across and, amazingly, it is calm with light winds and clear skies.
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