Latest digests
how does snow fall from the sky

In Colorado, graupel is fairly common due to the higher altitude, but it can form anywhere that it snows. It’s just more difficult at lower altitudes because there is a greater height separation between the super-cooled water high above and the ground below. At higher altitudes, like Denver and Colorado Springs, the graupel has less distance to travel before it hits the ground. Conversely, graupel will have to fall an additional mile after forming before it reaches the ground in a location that’s closer to sea level.

David Rothery is author of Planet Mercury - from Pale Pink Dot to Dynamic World (Springer, 2015), Moons: A Very Short Introduction (Oxford University Press, 2015) and Planets: A Very Short Introduction (Oxford University Press, 2010). He has received funding from the UK Space Agency and the Science & Technology Facilities Council for work related to Mercury and the European Space Agency's Mercury orbiter BepiColombo. He is co-leader of the European Space Agency's Mercury Surface and Composition Working Group, and a Co-Investigator on MIXS (Mercury Imaging X-ray Spectrometer). He is Educator on the Open University/FutureLearn Moons MOOC and chair of the Open University's Planetary Science and the Search for Life course.

Being only a few micrometres in size, ice particles falling from the clouds would would drop at about only a centimetre a second. This allows more than enough time for them to evaporate before reaching the ground (strictly speaking, the process should be called “sublimation”, because the ice goes directly to vapour, without melting first). Overnight and seasonal frost spotted on Mars have been explained by water-ice particles falling quickly because they had been made temporarily larger and heavier by an outer coating of frozen carbon dioxide from the atmosphere.

This leads to rapid downdrafts of air, travelling at about 10 metres per second, which could carry ice crystals to the surface too quickly for them to “evaporate”. However, the snow layer would probably be thin and not last too long before it sublimes back into the atmosphere – where it could form new clouds and snowfall.

Very likely related to the seeding of the atmosphere to form clouds and produce snow. Probably part of the geoengineering experiments that are ongoing worldwide. Dominica experiment 2011., DOMEX2011 They can make anything happen weatherwise including weather weaponization.

The effect of gravity on this is similar to that of a feather, which is caught by the air and wafted to and fro.  So while a raindrop is concentrated and answers the downward call of gavity to fall straight through the air, a snowflake enjoys its meandering, liesurely trip from the troposhere (or somewhere up there) to its final random resting place below.

Thus the action pictured by "dropping" is not appropriate for snow.  The infinitely variable shape is referred to as a flake, due to the generally flat shape and individuality of the particles.  Like a "flake" of something sliced off the larger part, like a flake of soap.

Eventually as the hailstone gets bigger or the updraught weakens, it will be too large for the cloud to keep suspended and will fall to the ground as hail. Depending on surface air temperatures, the hail may start to melt and soften and fall as 'soft hail'.

Snow typically forms when water vapour is rapidly cooled and turned into ice without going through the liquid phase. Although snow can form in a thunderstorm it can also form in any rain-bearing cloud.

Here’s how I understand it; when we have no snow, light sources like street lights illuminate the area around them, which is usually a dark surface. And when the sky is clear, the light has nothing to reflect off of and continues into infinity and beyond.


Related articles