(the page above is marked “5 hours ago”, and shows footage shot inside a car as hail falls, then afterwards shows the damaged windscreen + bumps in the car roof)
(I began writing this in the late afternoon on 4 June, but did not post until much later, as had much trouble confirming the info below)
I’ve never had hail as big as this hit my car, but I did once see the aftermath of such an event:-
I travelled to Shropshire a lot during the 1980’s, and on some occasions there was some extreme weather. As one example, I was travelling during the evening in winter on the M62 from Hull to Shropshire. It was snowing, and I was listening to the Radio 4 ‘PM’ programme. There is always a weather section, and they said that you could tell the temperature by the appearance of the snow. At about -15℃ (just above 0 Fahrenheit, which is approx -18 Celsius) the snow ‘glints’ (that is because the crystal structure of the snow changes at that temperature, and it becomes smaller & denser). Sure enough, as I got close to Manchester the appearance of the snow reflected in my car headlights suddenly changed, and instead of being all fluffy & white it became smaller & more ice-like. And I was only halfway there! Thank goodness that my car & it’s heater were reliable.
More temperature lore:- pure water can be cooled below zero and will stay liquid until -40 (Fahrenheit & Centigrade are also identical at -40); water needs what the meteorologists call a “nucleation point” to freeze. Just a speck of dust is enough to cause water to turn to ice at 0℃, but if it does not contain any contaminants, or suffer a trigger event (such as hitting the ground), then it will remain as water until -40.
The previous paragraph explains “ice storms” and “freezing rain”. The effects of day & night & seasonal change upon the atmosphere can cause large bodies of air to get lifted up and, as everybody that has climbed a tall hill knows, it is usually much cooler higher in the atmosphere than lower down. If that drop in temperature is sufficient to cause the air to fall below it’s “dew point” then some of the water that is (almost) always dissolved in air will condense out and become water. If the air is also very clean then that water will stay as water even if the temperature is below freezing and above -40. Such rain on hitting the ground, or hitting trees (or people!) will instantly freeze, and these are called “ice storms”. The weight of the ice on tree branches easily becomes sufficient to cause the branch--and sometimes even the entire tree--to collapse. I also know from personal experience that freezing rain on tarmac causes a surface even more dangerous than snow. It is commonly known as “black ice”, and the only sign of it at night is when the steering suddenly becomes very light. What is most important is NOT to use your brakes (you will end up spinning round & round in circles) but to simply take your foot off the accelerator & pray that the road does not curve before you stop.
The above is also responsible for Ice fog (rather than plain fog) when below -40. However, here’s a curiosity:- at -30℃ (-24℉) pure water will stay as water yet, if you throw boiling water into the air, it will freeze before it hits the ground. Don’t believe me? Here is the proof:
Some final temperature lore: In Jack London’s story “To Build a Fire”, set in the Yukon, Alaska, he says that to know what temperature it is you should spit. If the spit explodes when it hits the ice, then it is 50 below (-46℃). If the spit explodes (freezes) *before* it hits the ice, then it is 75 below (-60℃). (It is really important to know the difference if you are wet - you will die in a few minutes if wet & 75 below).
So, back to Shropshire!
I arrived at a place with a number of cars in the forecourt. Most of those cars had masses of dints in the roof (curiously, the windscreens were OK). The chap told me that it had hailed a previous day (I had heard of a tornado, but not hail), and that what I was looking at was the result. He also told me that some greenhouses had been trashed.
Those are mighty large lumps of hail in the picture at top.
--------- Alex Kemp