Beicology: Why Does it Hail in Summer?

If you were out and about on Jun 12, then you might have had the misfortune of being caught in one of Beijing’s summer hailstorms. The capital is no stranger to hailstorms and a few each summer are pretty much guaranteed, but why does hail form in the summer when it's usually hot?

Well firstly let’s take a look at how and why hail actually forms. Hail forms when updrafts (strong currents of rising air) carry water droplets to a high enough altitude to freeze. At this high altitude there are already supercooled water droplets present and these adhere to surface of other water droplets, forming layers of ice around it. 

Once a hailstone reaches a large enough weight and size, gravity will begin to act on it and pull it down, however it could be pulled up again by another strong updraft and continue to grow. Therefore when there is an especially strong updraft, large hailstones can form. 

These strong updrafts occur in cumulonimbus clouds, often called thunderheads or storm clouds which are usually recognisable by their dark, ominous appearance. Although these clouds can occur in winter, they are more commonly seem in summer storms or in tropical areas, hence why Beijing normally experiences hailstorms during summer.

This most recent hailstorm in Beijing had some pretty impressively large hailstones, and there were reports of some even being the size of eggs. Videos and photos went viral online showing an array of these large hailstones and the extensive damage some of them had wreaked upon the city. 

Now, although an egg-sized hailstone may seem to be a rather unusual occurrence, this is nothing compared to a few years ago when there were reports of “coronavirus shaped hailstones” raining down on Beijing. Yes, back in June 2020 during the Dragon Boat Festival there was a particularly violent hailstorm featuring these distinctly shaped stones.

Given that this was still during the pandemic’s relatively early days, many netizens couldn’t help but wonder if this was some kind of apocalyptic sign from the gods. It looks like this time 'round, though, aside from the large size, the hail was relatively normal and with the current rise in Covid cases linked to the Heaven Supermarket outbreak, we can at least be thankful that there isn’t any sign from actual heaven that Covid is falling from the sky. 

READ: Beicology: Beijing Meets All National Air Quality Standards for First Time

Images: Weibo, Katie Coy