How to predict a thunderstorm without Internet access?
április 15, 2009 1 hozzászólás
In one year, there are 1000 people being struck by lightning, the 50% of this events are fatal. In many cases, the main reason of being hit by lightning is the unfair knowledge about how and when thunderstorms could appear. Most people believe the storm is unpredictable without following radar images and forecast modells on the Internet. But it is actually predictable! Imagine that you are on a field on a holiday with your friends and family. You don’t have Internet access, but you can see the sky! In the sky the air humidity and stability is visible! The sign of unstable weather is a cloud type that is called ‘altocumulus castellanus’.
Main conditions of a thunderstorm are high humidity of the lower level, unstable state of the middle level and calm and cold air in the high level of the atmosphere. There are vertical circular winds in the middle level which gives the shape of castellanus clouds which even makes the air more humid, so it will fasten the thunderstorm developing process. Usually you can see castellanus clouds in the morning (around 7-9am) and the storm arrives at midday. But there are exceptions: rarely the castellanus appears in the evening and the storm arrives at night. Severity of thunderstorms depends on the temperature. below 20 °C (68 F) thunder and lightning is very rare. Only 2-3 lightning bolts the whole time of the storm. Between 20 °C and 25 °C (68 F and 77 F) Storms become stronger. at about 25 °C lightning flashes in every minute. The warmer the air, the more violent the storm. At 30 °C (86 F) There are lightning flashes in every 30 seconds! Towering cumulus congestus clouds are signs of the arriving storm in about 10-20 minutes. In 27th of June, 2006, I observed a developing thunderstorm and took a series of photographs of it:
The cloud became a cumulonimbus calvus (5 minutes lasted) The cloud became a cumuloninbus incus (20 minutes lasted) Lightning bolts appear Video version: http://www.youtube.com/watch?v=f_uIbIP9AQY