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N00L99999 t1_iusal3w wrote

Reply to comment by Diligent_Nature 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

> Only for water.

Not just for water. Subzero Celsius means rain turns into snow, and also that windscreens start freezing, thus requiring pre-heating to de-ice it.

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girhen t1_iuskwxy wrote

>Not just for water. Subzero Celsius means rain turns into snow, and also that windscreens start freezing, thus requiring pre-heating to de-ice it.

That's because rain and snow are... water.

Not arguing that his comment fighting over 0C being important only for water isn't silly because there's a lot more water in your car than just coolant (vapor, ice, snow, etc affect more than just driving conditions), but pointing out rain vs snow is still just talking about water.

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N00L99999 t1_iuslthw wrote

Of course.

But the comment I was replying to also mentionned to use “antifreeze” to avoid pre-heating, as if the problem with pre-heating was liquids.

It’s not.

The problem is the snow, which starts at 0 Celsius.

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girhen t1_iuso6wn wrote

I mean, that's fine. The way you said it didn't make much logical sense to me.

I'd have told him that it's not about the engine's water freezing (or not), but rather about warming the engine to deal with the environmental effects of freezing water and general cold. Defrost the ice on the windows, stop fogging windows, and the fact that most humans aren't happy in freezing temperatures. Skip the part that reads like it's not about water freezing, but that it's about water freezing.

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Fearlessleader85 t1_iut4wjl wrote

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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