Rotation of the Earth/Freezing at Night

This is a question I have thought about for a while: How much slower would the Earth have to turn for the side away from the sun to freeze at night? As it is, I think no side is away from the sun for no more than 12 hours (I don’t mean like Alaska, with its six months of light and six months of dark, I mean like Texas, or Hawaii). Would a night time lasting 48 or 72 hours be long enough for winter like conditions to set it, despite the heat the Earth had absorbed during the day? Or would it take longer? Or would the longer day heat the Earth enough to withstand the longer night?

There are too many variable factors to be able to give a simple answer. You’re excluding the polar areas, but there’s still a lot of room in the middle. There will be wide variations between Ecuador, France, and Denmark, for examples. And what time of year do you mean - December, June, or April? Not to mention elevation - many mountains aresnow-capped all year round.

Funny you should ask this. I just read the book “The Science of Star Wars”. Okay, I know you are thinking “Uhh … Glitch, this is science fiction”, but actually the book dicusses the things in Star Wars as a “Could they exist?”. The book is written by a former (?) NASA scientist and he quotes a lot from other scientists so he seems to have a certain degree of intellectual honesty.

Anyway, I will confirm this tonight when I get home to check the book, but it seems to me he says the critical day for life to occur has to be between 7 Earth hours to 4 Earth days. Any slower and there would be too great a variance of temperature. Any faster an there would be too much atmospheric turbulence.

Of course, that doesn’t really answer you question as to how slow the Earth would have to turn in order for the night to cause things to freeze, but maybe it helps answer the OP a little.

“Glitch … Anything.” - Bob the Guardian

More likely to be “The Physics of Star Trek”, but I obviously can’t tell you what you read.


Nope, definitely the “Science of Star Wars” since I am not enough of a fan of Star Trek to read “The Physics of Star Trek”.

It is in Chapter 1 dealing with planetary development and whether there could be a Galactic Republic/Empire of thousands of worlds.

What do you mean how much slower? Plenty of places on earth freeze overnight already.

As others said it’s a complex question with a lot of variables. Cloud cover is a good one. Clouds can prevent night heat loss. With a clear sky it’s not uncommon for desert locations to freeze at night.

True, but Texas and Hawaii don’t (see the OP). I think (and the original poster can correct this) but to rephrase the OP:

How much slower would the Earth have to spin such that the night section of the Earth, in regions which on the real Earth are warm, would be freezing?

Glitch, I was just pointing out that the question needs to be refined to get a useful answer. Lots of warm places have overnight freezes which meets the criteria somewhat. If your standard is sea ice at the equater that’s another matter.

Italics mine.

How much clearer can that get? I.e. what would the Earth’s spin have to be like so that Hawaii would get winter like conditions every night.

I couldn’t find an exact amount of time that would cause winter like conditions, but there certainly would be an certain day/night cycle that would cause such.

From “The Science of Star Wars”

As a rough guess, I would say the day/night period would probably be at least a week or two before things would start getting real cold (winter like) during the night cycle, but that is just a guess.

I don’t think it would take anything much longer because the heat from the Earth would bleed off pretty quickly and then start to diminish.

You want facts rather than caveats, one assumes. OK, measure the
average temperature at sunset and before sunrise for your location of
interest. If you do enough averaging you will cancel the effect of
local weather, cloud cover, folks leaving their fridge door open,
whatever. Now a reasonable assumption is that the temperature falls
exponentially, T_dark/T_light = Exp[-a t_dark], where t_dark is the
time it has been dark. By using your data, solve for a. Then use the
equation to figure out how big t_dark has to be in order for T_night
to reach freezing.

In LA the temp falls from about 295 K to about 285 K right now, when
we have about 12 hours of darkness, which suggests a = 0.003/hour.
Thus it would take about 25 hours of darkness for the temperature to
fall to freezing and about 48 hours to fall to 0 F, corresponding to a
nasty winter’s day in New England. In 4 days the temperature would
fall to -125 F, which is about the coldest it ever gets in Antarctica.

Oh, also, rapid rotation would not lead to rapid temperature changes. If you motorize your rotisserie, the roast cooks more evenly, right? Same thing with a planet. Exceedingly rapid rotation would lead to enhanced Coriolis force on wind patterns, however, which might lead to weird weather.

I would venture to guess that there would be no defintive answer to this question, or more accurately, no way to even make much of a guess.

The reason the Earth is not like the Moon, where the temperature will go from insanely hot to unbelievably freezing when you go from a sun-up to sun-down position is because of it’s lack of atmosphere.

We have an atmosphere, one which creates a green house effect thast means that even in the absense of direct sunlight, the area gets cooler at a much slower rate.

Now, what I’m thinking isthat if we were to significantly alter the orbit time of the Earth, the principals of the green house effect would also change, probably significantly.

The reactions of the planet below to this change would also effect the atmosphere. As in, plants dying from lack of sun for extended periods of time, and the lack of that they put into the air would change it. Or plants getting more hearty to coompensate would also do this. And mammals would also have a lot to do with this change, as our lives would change based upon the changes in vegitation.

Even if you are assuming that it would be an overnight thing where the Earth would slow down it’s rotation, I would think very soon, all bets would be off on how the atmosphere reacts to it.

And if the atmosphere changes, so does the variables which you would need to take into consideration if attempting to apply a mathematical equation as your hypothesis.

Yer pal,