"Zero" degrees

One of our local weathermen made a joke on the air last night: Our low today was zero Celcius. Basically he said:

“…contining cloudy and cold. Today we reached zero, and tomorrow it will be twice as cold…(laugh)…”

I know it’s a joke, but is this possible. Twice as cold as zero would mean zero, doubled, which is still zero. A reasonable joke, but still a good thought starter!

With God as my witness, I thought turkey’s could fly.

I think “The Master” might have addressed this, but this is my view of it:

The concept of “twice as cold” or “twice as hot” assume you’re using a thermometer that starts with 0, like Kelvin.

So, 0 Celsius is 273 (or so) Kelvin.

So what temperature is twice as “cold” as 273 K?

Nothing. The question is meaningless.

You could rephrase it into something like “Today is only half as cold as it’s going to be tomorrow.”

Then you would get some number like 136 K, which is -136 C and I don’t feel like using the formula at this moment (F = 9/5*C + 32) to determine Fahrenheit.

I would think the only objective meaning of “twice as cold” would be “half as hot”, i.e. having half the temperature measured on the Kelvin scale. So, since zero degrees Celsius equals 273 Kelvins, twice as cold as that would be 136.5 Kelvins, or -136.5 degrees Celsius. Which is pretty nippy.

A valid subjective meaning might be, “twice the temperature deficit relative to the norm”. So if your town averages 20 degrees Celsius, and today it’s 10 deg., it’ll be twice as cold tomorrow if it reaches freezing.

But it sounds like the weatherman was just trying to be funny.

Any similarity in the above text to an English word or phrase is purely coincidental.

To slightly modify Boris’ answer, I’d suggest it might be thought of as relative to room temperature (72 degrees F) rather than a local mean. I (sort of subconsciously) relate heat and coolness to room temperature, even if nobody else does. But of course I agree it was a joke.