Question submitted by Sarah Renzoni
(West Vancouver, BC)
In the wonderful words of Einstein "it's all relative"!
You see on a small scale, relative ambient air temperatures are the driving force of air circulation. As your mother notes, Ella, warm air rises and cold air sinks. However on a much much larger scale, (weather systems and atmospheric layering scale) the air thins with height. Less air means less trapped warmth. So the higher you go, say up a mountain, generally the cooler the air. However this is not always the case.. sometimes a layer of warm air can be found on top of a mountain - what is meteorologically known as an "inversion". This occurs where cold arctic has sunk and travelled into a valley floor.. forcing warm air to rise above it.. much like as Mum notes, happens with your bunk beds!
Hope this answers your question!