How are kitties able to handle the heat?

When I was with my last girlfriend, we had an air conditioner on the main floor and it would only cool off the main floor. The basement was nice and cool, but, the upstairs was an inferno. All of our cats chose to sleep upstairs. Their bodies all stretched out straight whilst sleeping and they seemed to love it. I could never understand that. Both of our pooches, though, slept right in front of the air conditioner.

It’s almost 11 in the morning here, and it’s already 90 degrees outside. Again, my (indoor/outdoor) cat, Frank, is outside, lying on his side all stretched out. He’s lying in direct sunlight and purring away.

Why do they prefer the (hot, hot) heat?