Poland Meteorology FDC

Poland FDC
Name: The Meteorological Phenomena
Date of Issue: 25 April 2008

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: hydrometeors (rain, hail, frost, tornado), lithometeors (dust or sand blizzards or whirls), photometeors (halo, rainbow, mirage), electrometeors (storm, lightning, aurora borealis)

Meteorology - a branch of science, investigating the atmospheric phenomena. Based on the results of measurements of the main 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. Its results, or synoptic prognoses, are indispensable for the different sectors of country's economy, as in agriculture, for example, in order to avoid the catastrophic crops losses, or simply in the flight control.

Designs:
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.

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.

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.

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.

The new stamps and the FDC envelope
The presented here four-stamp series shows the beauty of meteorological phenomena as fixed on the photographs. The graphic layout suggests that the slides have been shown in such a way to enhance their contrast and colors. Each stamp presents one phenomenon representative for each of the above mentioned groups hydrometeors, lithometeors, photometeors and electrometeors. On the FDC envelope the similar slides can be seen as lying on the back-light table. Their evaluation and choice of the best ones is suggested by the magnifying glass nearby.

Comment: This set was issued on 25 April, the stamps on this FDC were cancelled by "25.04.2008" special cancellations. But my friend sent this FDC on 13th May, 18 days after issue day, and he only added 1.30 ZŁ definitive stamps on this FDC. That's meaning the cancelled stamps' postage is still valid after 18 days, and I think it could be longer than 18 days, do you know how long about it?