Define atmospheric pressure.

Define atmospheric pressure.

• A. The weight of a column of air above a point on earth, concentrated by gravitational attraction
• B. The weight of a column of seawater above a point
• C. The speed of wind at a location
• D. The density of air at sea level

Answer: (A)

Atmospheric pressure is the force per unit area exerted by the weight of the air above a point on Earth, pulled down by gravity. Imagine a column of air rising from that point to the top of the atmosphere—the weight of that column presses on the surface, creating the pressure we measure. This is why standard sea-level pressure is about 101,325 Pascals (1013.25 hPa); as you go higher, there’s less air above, so the pressure decreases. The other ideas describe different concepts: seawater would create hydrostatic pressure in a liquid, wind speed relates to dynamic pressure from moving air, and density is how much mass is in a given volume, not the pressure itself.

Atmospheric pressure is the force per unit area exerted by the weight of the air above a point on Earth, pulled down by gravity. Imagine a column of air rising from that point to the top of the atmosphere—the weight of that column presses on the surface, creating the pressure we measure. This is why standard sea-level pressure is about 101,325 Pascals (1013.25 hPa); as you go higher, there’s less air above, so the pressure decreases. The other ideas describe different concepts: seawater would create hydrostatic pressure in a liquid, wind speed relates to dynamic pressure from moving air, and density is how much mass is in a given volume, not the pressure itself.