Mateorological Phenomena FDC from POLAND

Name of FDC: The Meteorological Phenomena
Date of Issue: 25 April 2008
Details:Since the earliest times people used to watch carefully the nature, trying to foretell by the clouds or animal's behavior, for example, the oncoming storm, rain or drought. Nowadays we just look at the TV weather forecast while planning an excursion or simply choosing the suitable dress for tomorrow and to be sure if we would need an umbrella. The weather influences our general frame of mind, but we have no influence on it, either. Not infrequently the nature shows us its tremendous power in the floods or hurricanes, for example. But there are also many meteorological phenomena that may pass unwatched for us, and sometimes it is simply worth to look at the sky to see something beautiful and unusual.The meteorological phenomena as to their nature: hydrometers (rain, hail, frost, tornado), lithometeors (dust or sand blizzards or whirls), photometers (halo, rainbow, mirage), electrometeors (storm, lightning, aurora borealis)n parameters (such as the air temperature, humidity, and pressure together with the wind speed) and the data, provided by the radars, air probes and satellites the complex analysis (today mostly computer-aided) is executed of their complicated mutual influences.
1st Stamp-1.35 ZŁ: Sand blizzard: The sand being carried up high above the ground level by the strong, hot wind. It can be very arduous for the inhabitants of the desert areas.
2nd Stamp-1.35 ZŁ: Lightnings: The atmospheric electric discharges, born in the high rainclouds (cumulonimbus) in the result of the great temperature gradient and the strong wind. The lightning in fact is an electric spark, zeroing the charge difference between the cloud and the earth or between two individual clouds.
3rd Stamp-2.40 ZŁ: Rainbow:An arch of the diffracted sunlight. It emerges in the result of refraction, diffraction and the total internal reflection of solar rays in the small raindrops in the atmosphere. It is visible only if the Sun shines from behind of the observer and is sufficiently low (less than 40 degrees) above the horizon.
4th Stamp-2.40 ZŁ: Tornado:A great funnel shaped whirl of air and liquefied water vapor, reaching up to the clouds. It rotates with enormous speed (400 km/h, for example, and creates giant difference of pressure inside. If it touches the earth, it destroys everything on its way, leaving behind a few hundreds meter wide trace of ruins on a distance of some 10-20 km.
Remark:FDC was issued on 25th APR'2008 but posted on 13th MAY'2008 by regd post.