Weather Facts

Did You Know that Cold Air is heavier than Warm Air?

Cold air is much heavier than warm air and this is the basis for much of what we call weather. Did you ever notice after taking a hot shower, that when you first open the door to the bathroom, the cooler air from outside the bathroom comes in at the lowest level? Or how about when you open your freezer, you could feel the cold air just rush downward towards the floor. Cold air in the atmosphere behaves the same way and this is why it stays separate from air that is warmer. Why is cold air heavier than warm air? Cold air is denser than warm air. The molecules are packed closer together. The amount of water vapor in the air also affects the density of the air. The more water vapor that is in the air, the less dense the air becomes. That is why cold, dry air is much heavier than warm, humid air. You may have heard that a baseball or a golf ball will travel further on a warm, humid day than it would on a cold, dry day. Since the warm, humid air is less dense, the ball travels through it with less friction. Please read my posts on cold fronts and warm fronts which describe how the different air masses interact and the weather that is caused by them.