Find out how a tropical cyclone forms here.
The BBC published the predicted path of the super typhoon and predict that the typhoon will hit Vietnam over the weekend. The BBC have a short video clip on their website - link here and here.
The Philippines is a vulnerable country with thousands of islands spread across a tropical ocean. Although the population are only concentrated on 11 islands, they often find themselves in the path of typhoons. The population have a low GDP of $2587 per capita (2012) and authorities have warned dozens of provinces across the country to be prepared for possible flash floods and landslides.
According to CNN (report here) some of the most vulnerable people are those living in temporary shelters after the recent 7.1 magnitude earthquake displaced around a third of a million people from their homes on the central Philippine island of Bohol. Around 125,000 people have been moved to evacuation centres for safety.