Unlike other mammals, humans aren’t so good at conserving body heat. In fact, after being exposed to cold air or water, we lose heat rapidly.

In a video produced by BBC Earth, Oli Martin depicts what happens to the human body when it’s exposed to extreme cold. Through a thermal imaging camera, you can see how your body would lose heat outdoors in the winter; the red blotches signify areas of higher temperatures, and the green-to-darker colors are parts that are rapidly losing heat. In a snowstorm, below-zero weather, or simply a blustery day, several things are working against you to steal the warmth from your body: Evaporating water from your skin if it’s wet or covered in sweat; the natural process of heat moving away from your body, known as radiation; conduction, in which the body loses heat from touching something cold, like a concrete wall; and convection, or the wind whipping heat away from you.

Using a Selex Merlin thermal imaging camera, Martin stands outside during a snowstorm in the Scottish highlands for a little under three minutes, slowly taking off his layers — a jacket, shirt, and hat. First, the area around his neck remains red as long as possible; it’s one of the warmest parts of his body. As he strips bare-chested and extends his arms, first the extremities — the fingers and hands — turn green. When zooming close up to his body, we can even see the dark spots of snow hitting his chest. As the specks of cold suck heat away from his skin, the dark colors begin to spread like a disease.

What would it take to become hypothermic? If your body heat drops from 98.6 degrees to 95 degrees Fahrenheit, you’re officially hypothermic and at risk of symptoms like slowed respiration and heart rate, confusion and dizziness, and a slow decrease of body temperature to as low as 80 degree Fahrenheit, when the ultimate organ shudown occurs.

“This thermal imaging camera allows you to vividly see how cold conditions can be so perilous,” Martin notes in the video. Indeed, cold weather isn't something to be careless about. As every inch of our bodies can quickly lose heat when exposed to freezing air, it's important to wear plenty of layers when venturing outside.