"Somewhere over the rainbow, way up high..."

With yet another imminent typhoon sending those trusty flag-hoisters scrambling for their no. 8 signals (clearly flag-hoisting is becoming a much more stable occupation for the young-uns to enter into than say, financial services; at least if you live in the South Pacific anyway), I've been wondering what exactly causes these crazy and somewhat frequent weather phenomena.

Obviously, if you're a lot more knowledgeable on such a subject than I, feel free to click onto The Economist or Sky Showbiz without further ado. Equally, if you have no interest whatsoever in typhoons and the like, you may also leave. The curse of the blog reader seems to be that the writer always assumes people will be interested in their subjects, no matter how self-indulgent or trivial they are!

Apparently influenced by the Cantonese word tah fung, which literally means 'striking wind', a Pacific typhoon is a tropical cyclone specific to the basin in the northwestern Pacific Ocean, home to the strongest cyclones on record.

So, having read several descriptions of how these babies come about, I'll try and de-science them here (because believe me, it gets a bit like school otherwise): Areas of low atmospheric pressure which are close to the earth's surface tend to produce thunderstorms and strong winds anyway. These areas then feed off of, and are driven by the heat given off when moist air rises and results in condensation. The reason typhoons happen over Hong Kong and the surrounding areas is that you need heat from the sun in the first place to make the moist air rise and evaporate. Presumably why there haven't been too many typhoons recorded in the English Channel...

It's then kind of a catch-22 system - the condensation means the wind speed increases, which, along with the low pressure, leads to more of the water's surface evaporating, and so even more condensation is produced. And then we start all over again.

Tropical cyclones (a.k.a. our friends the typhoons) only happen over water for this reason; they need the moisture from constantly warm water to keep the process going. If it hits land, it fizzles out pretty quickly.

As you can imagine, there's a lot more to the science than this, but I just wanted to share what I'd discovered. I need to be careful though; it seems that the more weather elements I experience out here, the more weather-obsessed I become! See what happens when you don't have a full-time job...

picture source: http://en.wikipedia.org/wiki/Image:Hurricane_Kate_(2003)-_Good_pic.jpg (apologies that the picture isn't an authentic Asian typhoon, I have limited resources and hopefully you get the gist!)