Here’s a few items of interest. Certain species of migratory birds, fish and insects can sense the Earth’s magnetic field and use magnetsome cells in their brains to orient themselves and navigate during migration. In Egypt, visitors breathing inside the great pyramid Chephren at Giza are contributing to its destruction. About 0.7 ounces of water vapor is exhaled per person, raising the humidity and damaging limestone blocks. A ventilation system is in place to alleviate the problem. Can you be allergic to cold weather? Some people may step outside on a cold day and break out in hives. To check for this, place a resealable plastic bag, filled with ice on your arm for two minutes. If an itchy welt appears, you need an antihistamine.