Tuesday, May 17, 2005
A Short Guide On Understanding TV Weather Reports
Today, I'm going to talk about the weather reports found on TV. For readers in Singapore, I know all this won't be totally relevant because Singapore's weather is always the same. It's so 'the same' that I can actually predict it with a high degree of accuracy most of the time. Still, if you watch CNN or stuff like that and they talk about the weather, this might help you catch a little bit of the action. The first picture above is easy enough. These are temperatures in degrees Centigrade reported by school kids. Next comes the forecast for the next three days. The first thing to note are the white lines. They denote air pressure in hectopascals. So anywhere along the line labeled 1020, the air pressure is 1020 hPa. When the lines are closer together, the 'pressure gradient' is steeper. Wind is formed when two areas have different air pressures. So, the wind will be stronger when the 'pressure gradient' is steeper. The next thing to note is the blue line with triangles. This line denotes a cold front. A cold front is cold air meeting warmer air, pushing up the warmer air. This might result in rain. You can't see it here, but there's actually a low pressure region just to the bottom left, out of the screen. (Click here to see the latest chart.) In the southern hemisphere, wind spirals cLockwise around a low pressure region. (The opposite happens in the northern hemisphere.) That means the wind will reach the land area (the bottom left of Australia) from the west. You can see the progression of the cold front for the three days. This cold front will be moving towards the mainland and hitting Australia from the west, bringing bad luck, uncertainty and rain. The last screen tells us the forecasted wind speeds at the coast. "N/NW winds" means wind speeds in knots, coming from the north and northwest. This is obviously a cursory look at things, so please correct me if I've made a mistake. There are useful tutorials, and also some weather education. The weathergirl today is Natalia Cooper.
Posted by jeffyen at 11:52 PM