Flying.... Why is the air density lower on a warm day? Is it because there is less moisture in the air?

Question

Flying.... Why is the air density lower on a warm day? Is it because there is less moisture in the air?

Answer 1

the air is actually less dense when its hot. hotter air can hold more water. the water molecules that replace the air molecules are actually less dense, believe it or not.

Answer 2

Hotter air is less dense.  The average kinetic energy of the gas molecules is higher when it's hotter, so the gas is "spread out" more, hence lower density

Most things have their density decrease as heated(in other words, they expand)

Answer 3

PV=RT is the universl gas equation where 'P' is pressure,'V' is th volume ,'R' is the gas constant of dry air and ' T 'is the temperature(absolute temperature).Here if we substitue,1/V for the density 'd', we get,

d=P/RT, which means if the temperature ' T ' is more.,the value of 'd' decreases.So,density is lower on warm days as air temperature is more.

The moisture may be less or more on a warm day.So, that is not the reason.But warm air can hold more moisture than cold air and this warm, moist air will be lighter than dry air.Hence only if moisture is more on a warm day,the density will be less.