Mammals are pretty amazing creatures

We're warm blooded, which gives us lots of advantages. For instance, unlike reptiles, we don’t need to bask in the sun before we get going.

The tradeoff...

The tradeoff is that we use a huge proportion of the calories we consume every day just keeping our bodies at a stable 37ºC. And we lose a lot of that heat to our surroundings. We're a bit like human hot water bottles.

The human body loses heat in three ways.

Conduction

When your finger touches something cold, for instance something metal, heat flows from your finger to the metal until both are the same temperature.

When you put a metal spoon in a boiling pot, the spoon heats up pretty quickly. Do the same thing with a wooden spoon and it takes a long time to even get warm. This is because wood doesn’t conduct heat very well, compared, for instance, to metal. Materials that are poor conductors are called insulators. These include ceramics, wood, plastic foam, wool and even air.

Convection

Just by standing in a room we’re heating it. The temperature of our skin heats the air next to it. That air rises, and is replaced by cold air. The rate of heat loss is increased when the air is replaced faster. That's why we get wind chills on blustery days.

Convection is the reason why we wear clothes (well, it's one of the reasons, anyway). Wearing clothes reduces heat loss by trapping warm air next to our skin. Different materials have different abilities to trap air. Wool's crimped structure traps far more air than cotton, making it a better insulator, and therefore keeps us warmer. All sorts of synthetic fabrics have been designed for different purposes, from watersports, to athletics to alpine hiking.

Radiation

Radiation is what we call the transfer of heat by waves of light. Most of the heat put into a room by an open fire is in the form of radiation.

Radiation is how energy from the sun reaches the Earth. About half of the total energy from the sun reaches the Earth as infrared radiation – the other half includes many more types of radiation, including ultraviolet and visible light (although, visible light actually only makes up a tiny part of the spectrum).

'Seeing' Radiation

Some animals, such as snakes, have the ability to 'see' infrared radiation, which allows them to track prey by heat.

Although, they don’t use their eyes to do this – they have sensing pits just above their mouth. We've developed thermal imaging systems that allow us to do much the same, except we use them to track weather patterns or understand how climate change is affecting the Earth.

So...

Next time you're on the DART take a look around – you might appreciate how hot everyone really is!