Question

How does density of the atmosphere relate to air pressure?

Answer 1

When we go to a region of high altitude, we experience altitude sickness and insufficient oxygen for breathing (anoxia). This is explained by Boyle’s law for gases.

Complete answer: Boyle’s law for a gas states that pressure of a gas, at constant temperature is inversely proportional to the volume. That means as pressure increases, volume decreases. Also we know that density is the result of mass upon volume of any substance, so volume is also inversely proportional to density, so, density decreases and volume increases.
Now, through combined gas law, PV = nRT, we know that pressure is directly proportional to temperature, increasing the temperature, pressure also increases, and so volume decreases, which means that density increases. Therefore, density is related to temperature.
Now, when we observe an area of high altitude, the place is colder, there atmospheric pressure is lower hence, the density is also lower. When pressure increases, the temperature also experiences an increase, and so the density of the air increases.
Hence, it can be accounted that when there is decrease in the air pressure, the density of the atmosphere also decreases, also temperature decreases.

Note: Due the reason that density is related to temperature, it is observed that colder air is less dense than warmer air. At high altitude or hilly areas, colder air is in abundance, so the density of the atmosphere is lower in those areas.