Under Pressure: Atmospheric Pressure Explained Quiz

If gravity pulls gas molecules toward the Earth, and if those molecules have mass and weight, then the cumulative force of all that air pressing down on an object is what defines atmospheric pressure.

If gravity pulls the majority of air molecules close to the Earth's surface, and if you move to a higher elevation where there are fewer molecules above you, then both the density of the air and the pressure it exerts must decrease.

If scientists need to quantify the weight of the air to predict weather changes, and if a barometer is the specific tool designed to detect changes in air force, then the barometer is the correct instrument.

If a high-pressure system involves cool air sinking toward the ground, and if sinking air warms up and prevents water vapor from condensing into clouds, then high-pressure areas are naturally associated with clear weather.

If liquid water needs to overcome the weight of the air to turn into a gas, and if there is less air pressure holding the molecules down on a mountain, then the water can escape into a gaseous state with less heat energy.

If 14.7 pounds of air are pushing on every square inch of our skin, and if our internal fluids and air are pushing outward with the same force, then the pressures are balanced and we do not feel crushed by the weight.

If nature moves toward a state of balance, and if high-pressure air has more force than low-pressure air, then the air will physically flow from the stronger area to the weaker area, creating wind.

If adding heat increases the kinetic energy of molecules, and if those molecules bounce off each other with more force and move further apart, then the air becomes less dense as it warms up.

If air pressure is created by the presence and movement of gas molecules, and if a vacuum contains no molecules at all, then there is nothing to exert force on a surface, resulting in zero pressure.

If air is a gas that can be compressed, and if the layers at the bottom are supporting the weight of the entire atmosphere above them, then those bottom layers will be squashed much more tightly than the thin air at the edge of space.

If the atmospheric pressure outside your eardrum drops as you go up, and if the air trapped inside your middle ear is still at a higher pressure, then the eardrum will bulge outward until the pressure is equalized, causing a pop.

If the entire weight of the Earth's atmosphere is pressing down on the very bottom layer, and if that bottom layer is at the lowest elevation possible (the ocean surface), then the air molecules there will be squeezed into the highest density.

If a storm is part of a low-pressure system where air is rising away from the surface, and if rising air reduces the weight pressing down on the barometer, then a drop in the reading signals that stormy weather is on the way.

If the atmosphere is made of gas layers held by gravity, then the troposphere, stratosphere, mesosphere, and exosphere are all valid regions where pressure exists; however, the mantle is a solid/liquid layer inside the Earth.

If meteorologists want to visualize areas of high and low pressure, and if they draw lines connecting all locations with the same barometric reading, then those lines are known as isobars.

If air density is higher at sea level, then each breath contains more molecules; if density drops at high altitudes, then there is less oxygen available in each lungful, which makes breathing difficult for the human body.

If you remove air from inside a straw, you create a low-pressure zone; if the atmosphere is pushing down on the surface of the drink with higher pressure, then that force will push the liquid up into the straw to fill the gap.

If pressure is the weight of the air, then it depends on gravity and mass; if temperature changes how fast molecules move and elevation changes how much air is above you, then all these factors determine the pressure.

If planes fly where air is very thin (low density), then the cabin must be pressurized for safety; if the shape of the wing creates a low-pressure zone on top and high-pressure on bottom, then that difference creates the lift required for flight.

If the standard unit for pressure is defined as one Newton of force applied to one square meter of area, and if that unit is named after Blaise Pascal, then the Pascal (Pa) is the correct term.