The coldest atmospheric layer is the ; the hottest is the .

I believe that the long word:


is actually all the options without a space:

stratosphere
thermosphere
troposphere
mesosphere

And the coldest is the mesophere -the temperature is around -90 degrees.

The warmest is one of the following:
(from
. )


thermosphere
mesosphere
troposphere
stratosphere.

The warmest is Thermosphere: it reaches up to 1500 degrees.

Did you know it's illegal to own only one guinea pig in switzerland?   : )