Now, holding the cardboard in place with one hand, carefully turn the glass upside down. Anyway, if you carefully release the cardboard . . . Air is pressing up on the cardboard with enough force to hold the water in the glass. Friday Wind is created when air moves from areas of high air pressure to areas of low pressure. These differences in pressure are caused by uneven heating and cooling of the air.
Warm air is lighter than cold air so it rises, causing cooler air to flow in beneath it.
Sometimes you can feel this taking place in your house on a cold winter day. Cold air may get into the room through windows or under doors. This phenomenon is called a convection current. Lest you think I'm full of hot air, come to see Montshire's new exhibit AirPlay, which opens on Saturday.