Hurricane? Cyclone? Typhoon? Here's the difference Haiyan, the world's strongest typhoon of the year, slammed into the Philippines early Friday. A POWERFUL typhoon hit the Philippines on Friday and moved out to the South China Sea. Why is this one referred to as a typhoon? Is there a difference? Essentially, they're all the same, officially tropical cyclones. But they just use distinctive terms for a storm in different parts of the world. Hurricane is used in the Atlantic, Caribbean Sea, central and northeast Pacific. They are typhoons in the northwest Pacific. In the Bay of Bengal and the Arabian Sea, they are called cyclones. Tropical cyclone is used in the southwest Indian Ocean; in the south-western Pacific and south-eastern Indian Ocean they are severe tropical cyclones. This early Thursday, Nov. 7, 2013 satellite image shows the eye of Typhoon Haiyan, off the coast of the Philippines. A storm gets a name and is considered a tropical storm at 63km/h. It becomes a hurricane, typhoon, tropical cyclone, or cyclone at 119km/h. There are five strength categories, depending on wind speed. The highest category is 5 and that's above 249km/h. Australia has a different system for categorising storm strength. If they are north of the equator they rotate clockwise. If they are south, they rotate counterclockwise. The Atlantic and central Pacific hurricane seasons are June 1 through November 30. Eastern Pacific are from May 15 to November 30; north-western Pacific season is close to all year, with the most from May to November. The cyclone season in the South Pacific and Australia runs from November to April. The Bay of Bengal has two seasons April to June and September to November. Government forecasters said Thursday that Typhoon Haiyan was packing sustained winds of 215 kilometres per hour and ferocious gusts of 250km/h. The north-western Pacific where Typhoon Haiyan has just hit. A normal year there involves 27 named storms. Haiyan is the 28th named storm and there has already been a 29th. By comparison the Atlantic averages 11 named storms a year and this year there have been 12, none of them causing major problems. The lists are maintained by the World Meteorological Organisation; the names are ones that are familiar in each region. Names are taken off the list and replaced to avoid confusion if a hurricane causes a lot of damage or deaths. For example, Katrina was retired after it devastated New Orleans in 2005. The Philippines has its own naming system, so Typhoon Haiyan is also being called Yolanda. The name Haiyan means "petrel," a type of seabird, in Chinese. The seabird lives over the open sea and returns to land only for breeding. During an El Niño - when the central Pacific is warming - there are fewer Atlantic storms. El Ninos shift where storms form, but not the number, for the northwest Pacific and the southwest Pacific. The central Pacific gets more storms during El Niño and the year after. This year has neither an El Niño nor its opposite, a La Nina. It is a neutral year.