You didn’t know that air weighed anything? Well, it does, and we call that weight air pressure.
At sea level, the average air pressure, or weight of all the earth’s atmosphere pressing down on one square inch of ground, is 14.7 pounds. This pressure, or weight varies with time and weather.
Fair weather is associated with high pressure (more weight), and bad weather (rain) is associated with low pressure (less weight). The higher you go above sea level, the less air there is directly overhead, therefore the less weight, or pressure.
Three and a half miles above sea level air pressure is cut exactly in half. Seven miles up, air pressure is only one fourth what it is at sea level. Since many jet planes fly at 30,000 or more feet above sea level, you can see the value of pressurized cabins.
The same thing happens with the density of air. At 100 miles above sea level, the air is so thin that it is a more perfect vacuum than anything a scientist can make in a laboratory.
Related Posts
-
Which has more pizza a ten-inch pizza or two seven-inch pizzas?
Next time you hear someone complain about never using the math you learned in school in real life, remember this question. You'd think the two smaller pies would have more, but that would…
-
Does the Air Around Us Weigh Anything?
Yes. Although we think of it as light, the air has heavy mass. Because the air is held to earth by the strong pull of gravity, it has a total weight of more…
-
How much water does it take to make an inch of snow?
If it's average snow, not too wet, not too dry, you'd need about a tenth of an inch of water to make an inch of snow. The general rule is that one inch…
-
What 12-Inch-Long Sea Creature Can Kill a Huge Shark?
That bold act is accomplished by the sea hedgehog. Getting its name from the land hedgehog, a small insect-eating mammal with sharp spikes on its back, much like a porcupine, the sea hedgehog…
-
How Much Water Is There in an Inch of Rain?
Meteorologists, or weather experts, measure rainfall and snowfall in inches. They let falling rain collect in a cylinder, and can tell how many inches have fallen by seeing how far the rain fills…
-
Where Did the Expression “Three Square Meals a Day” Come From and What Does it Mean?
In the eighteenth century, a British sailor's sparse diet consisted of a breakfast and lunch of little more than mouldy bread and water. If he were lucky, the third meal of the day…
