On Monday, Nate talked about basic wilderness preparation and what to take care of first in a survival situation. After air, what’s the most urgent priority? Shelter!
Today, we’ll talk about the science of staying warm and dry, and learn from animals. Then, we have an experiment: can you build a shelter that stays warm?
What makes a good outdoor shelter?
You might think about how comfortable the shelter is, or how protected it is. But one of the most important elements of a good shelter is how insulated it is.
Insulation is material that slows the loss of heat.
It is much harder to survive outdoors in the elements when your body is not at the ideal temperature.
Too much heat loss can even lead to hypothermia, a potentially deadly condition in which your body is way, way too cold.
The ideal body temperature for humans is between 97.7 and 99.8 degrees Fahrenheit. To stay at this temperature, our bodies constantly adjust themselves. We might sweat or shiver to cool off or warm up. Other warm-blooded animals, like deer or birds, do this too.
In contrast, cold-blooded animals like lizards and turtles can’t control their body temperatures internally themselves. They have to use the outside environment instead. If you see a turtle basking in the sun, it is using the sun to regulate its body temperature!
We want to keep as much heat as we can in our shelter! To do this, we have to slow down conduction.
Conduction happens when two objects of different temperatures touch each other. Heat moves from the warmer object to the colder one. In a shelter, this could be heat traveling from your warm body to the cold ground.
Insulation slows conduction. Fluffy materials that trap air inside are good insulators: think of piles of leaves, bubble wrap, down feathers inside a coat, or bubbly styrofoam. The trapped air is a barrier for heat transfer between two objects.
In winter, this is why we humans wear extra layers of clothing! Clothing itself does not provide heat. But air gets trapped in a few places: Air gets trapped in the fibers of your shirt, or the fluffy stuffing of your coat. And air also gets trapped in between your layers of clothing, such as between a coat and a long-sleeve shirt. These air pockets stop heat from leaving your body and escaping into the colder air.
If you get cold easily like me, I also like to wear a thick hat, scarf, gloves and multiple layers of shirts over my coat when I am outside in winter. The more layers I wear, the warmer I feel because all those layers add extra insulation – which means less heat escaping from my body into the colder winter air!
When you are building your shelter, keep conduction and insulation in mind. Where are warmer objects (like people) touching colder objects (like the ground or air)? Add insulation in those places to prevent heat loss!
Animals Build Insulating Shelters Too
Wild animals might not understand the exact science of heat loss like we do. But they do understand that heat loss is dangerous.
Just like humans, animals also insulate their shelters to prevent heat from escaping their warm, cozy homes!
What Do wild animals use to insulate their nests or shelters?
Birds use a wide variety of materials to insulate their nests. Check out your local bird nests to see what materials different species use!
Some examples of nest insulation include:
- dried grass
- animal fur
- plant fibers.
Squirrels use leaves to insulate their nests. Their nests, or dreys, look like big messy leaf piles in tree branches. Our shelter experts, Joe and Nate, recommend humans use 6 inches of leaves on the ground of your shelter and 6 inches on the roof to stay warm!
Some mammals have thick fur that insulates them. Deer have hollow fur. Each hollow hair has air space inside. This prevents heat loss–similar to humans wearing multiple clothing layers!
Beavers keep their lodges insulated in winter. They use mud to seal any cracks where cold air might come through. Then, their family’s shared body heat keeps the inside lodge temperature warm.
They have to be careful to not all leave the lodge at once to go foraging for food. Otherwise, the inside temperature would drop while they were away.
Want to create an insulating shelter that imitates a beaver, squirrel or bird?
Jello Baby Experiment Time
- pot for boiling water
- ziplock bag or cup
- insulating shelter materials of your choice (you can use some ideas from above!)
Your challenge is to prevent a bag of jello from cooling and solidifying. Use what you learned about insulation above. If you insulate your jello well, your jello baby will stay liquid for a long time!
If you can’t get jello, you could try this with a cup of water on a freezing night.
With a trusted adult, follow the directions on the jello box to boil your jello.
When your jello is no longer boiling hot, but still warm, pour your liquid jello into a ziplock bag and seal. This is your jello baby. Be a good jello parent and keep it safe and warm!
Gather some insulating materials. Use them to build a suitable shelter for your bagged jello. Play around until you find something you like.
Shelter materials could include: leaves, bundled up clothing, hats, moss, or twigs. But you can test whatever materials you want because this is an experiment. It might be interesting to see which materials are the LEAST insulating!
Place your jello baby inside the shelter once you are finished.
Pro-Tip: Get your shelter ready before making the jello, so your jello baby spends less time exposed to outside elements.
Check your jello baby every 10 minutes. Is it still in its liquid phase? Congratulations! You have insulted your shelter well enough to prevent the loss of heat and keep your jello baby warm.
Is your jello solidifying? Oh no! This means your shelter is not insulated enough. Add more materials to test which keep the heat from escaping your shelter.
See how long can you make your jello last. Eventually, all of the jello babies will solidify, since they can’t make their own heat. They are more like a cold-blooded animal than a warm-blooded human.
Let us know in the comments how your experiment turned out! What materials did you use? Was it successful at keeping your shelter insulated? Why or why not? We would love to hear how your jello baby survived.