"You may have noticed that your laptop gets a little hot when you have been using it for a while," begins John Carter. He goes on to give this helpful advice. "The battery doesn’t like being hot (it can go bad quickly), so it’s a good idea to do what you can to keep your laptop cool.
"Rock and metal are good conductors of heat. Wood is an insulator. If you are using your laptop on a wooden tabletop, the heat from the laptop is not being dissipated very well, so it would be a good idea to prop up the back side even a little to let air flow get under the laptop.
"If you’re using the laptop on your lap, your legs will get warm. Putting a pillow under the laptop to keep your legs from heating up is not the best idea either.
"A laptop cooler, one with fans in it, is the best way to keep your laptop cool. A dual fan laptop cooler is better than a single fan cooler. The problem with any laptop cooler is that it needs power, and it gets it from your laptop via a USB port.
"For the MacBook Air, you might not have any reason to use such a cooler since they stay pretty cool at all times. But the MacBook Pro (even one with an SSD drive) can get quite hot on a hot day."
John completes his advice with this, "For the sake of your battery if nothing else, keep your laptop cool."
But, John, how hot is hot? Looking at the iStatPro widget on my MacBook Pro gives me temperatures from 88 degrees in the Enclosure Base #3 to 121 degrees in the CPU Diode!
Two shakes later the reply flies in from John, "I would have to check the specs. It is different for each model. I would think that if you hear the fan running it's getting too hot." And he comments on the little "legs" under my computer. "The legs will certainly help to provide air cooling under the laptop."