The nature of silvery clouds is still not quite studied. Allegedly, they consist of the smallest particles covered with ice and therefore reflecting light. Emergence of such particles in the top atmosphere contacts emission of volcanic dust at strong eruptions or hit of interplanetary dust.!!!
Long researches of silvery clouds showed that these clouds, consist of the smallest kristallik of ice. It is very probable that as condensation kernels for icing of ice the particles of meteoric dust getting into our atmosphere from a space or which are formed as a result of destruction in the atmosphere of meteoric particles serve.
The water small pieces of ice weighed in the atmosphere are the reason of emergence of other shining objects - nacreous and silver clouds. Nacreous clouds - very thin translucent clouds which arise at the heights of 22-30 km, similar in a form with the chechevitseobrazny. These clouds have iridescent coloring owing to diffraction of light on particles of clouds - the overcooled drops or ice crystals. In twilight light scattered and reflected by these clouds is so bright that subjects on the earth cast noticeable shadows. These clouds are observed in northern highlands - Finland, Scandinavia, Alaska. Apparently, the air currents arising over mountains cause their origin. Owing to a rarity of this phenomenon nacreous clouds are a little studied.
As, most often silvery clouds were observed after strong, especially catastrophic eruptions, there was a hypothesis that they are caused by volcanic ashes. Very bright silvery clouds and the light white nights were noted after falling of the Tungus meteorite. According to supervision of 34 meteorological stations, the field of silvery clouds then had the area of 51106 km
Whirlwinds - clouds of this class, perhaps, the most effective, but meet they more rare than others. Vortex educations time remind freakish feathers of exotic birds, are sometimes similar to "funnels" with the dark middle.