Question

Residents in Conyers, Georgia, woke up to 27 degrees weather. Ms. Ausby had to let Snoopy outside to go potty. When she opened the patio door, she immediately realized just how cold it was outside. Explain if the cold air from outside entered the house, or if the warm air from inside the house exited. How do you know?

2. Flat Shoals Elementary took their first-grade students to the zoo. The students were studying cold blooded animals. Their first stop was the reptile area. In the reptile exhibit, students noticed that an alligator was lying in the mud in a sunny area. Melissa said that her per turtle lays on his "sun" rock like the alligator. Explain the method of heat transfer that the alligator and the turtle were using to warm their bodies. How do you know?

Answer 1

1) Both happened, but the immediate cold feeling is mainly because cold air from outside flowed into the house.
Why: when the door opens, air moves to equalize pressure and density. The outside air at 27°F is denser than the warm indoor air, so the cold air tends to spill in along the floor while the warmer, lighter indoor air rises and flows out near the top of the opening. This is convective/advective mass flow — warm indoor heat is carried out and cold outdoor air is carried in. You know cold air entered because you feel a cold draft at your feet/legs and you often see curtains or smoke pushed inward at the bottom of an open door — signs of colder, denser air coming in.

2) The alligator and turtle warmed mainly by absorbing solar radiation, and additionally by conduction from the warm rock if they were touching it.
Why: the sun heats them by sending electromagnetic radiation (not requiring direct contact), which their skin absorbs and converts to thermal energy. If the turtle/ alligator lie on a sun‑warmed rock, heat is also transferred directly from the rock to their bodies by conduction at the contact surface. These are passive heating methods characteristic of cold‑blooded (ectothermic) animals.