Mass of Air Estimation · BPhO 2010 #9

The key is to connect the familiar idea of atmospheric pressure to the weight of air itself. Pressure is force per unit area, so the $\sim 10^5$ Pa pushing down on Earth's surface tells you how much air mass is stacked above—and that same air fills the space around you. Rather than memorizing a number, estimate: a liter of air (roughly a water bottle) weighs about a gram, so a cubic meter (1000 liters) should weigh roughly 1000 times more.

The key is to connect the familiar idea of atmospheric pressure to the weight of air itself. Pressure is force per unit area, so the $\sim 10^5$ Pa pushing down on Earth's surface tells you how much air mass is stacked above—and that same air fills the space around you. Rather than memorizing a number, estimate: a liter of air (roughly a water bottle) weighs about a gram, so a cubic meter (1000 liters) should weigh roughly 1000 times more.