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Fearlessleader85 t1_iut4wjl wrote

Reply to comment by N00L99999 in 30 minutes of car preheating in sub-zero conditions produces as much particulate emissions as driving 97km in a gasoline car, or 20km in a diesel car “These findings do not suggest to stop preheating cars; instead, we could reduce the emissions by using similar methods that are in place for engine” by giuliomagnifico

That's also not correct. It can sleet or snow significantly above 0⁰C. Hail pretty much ONLY occurs well above 0⁰C. The coldest day I've seen hail on was in the high 30s F, the warmest I've seen it was around 80⁰F.

In dry air, pooled water can start freezing around 40⁰F fairly easily. In REALLY dry air, drops can freeze way above that.

It depends on relative humidity as well as dry bulb temp.

Edit: is actually dropping a mixture of rain, sleet, and hail outside my window right now at 39⁰F.

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