Air density and pressure confusion (written PPL)

[imcool]

Hello,
I have two facts in front me which is contradicting each other. i wish to resolve this confusion.
fact1 - Pressure drops as air gets thicker.
fact2 - air density increases as pressure increases and vice versa.

is any of my fact wrong?
if not, then how come fact1 is correct when its saying when air gets thicker i.e. denser pressure drops?

question2 air shrinks when it gets cold.
Here does shrinking mean denser? if yes.
then fact says temperature is proportional to air density again its a contradiction

Thanks for replying.
Best Regards

[Flying Low]

Fact 1 makes no sense. The more pressure there is, the "thicker" the air is. http://earth.rice.edu/mtpe/atmo/atmosph ... _what.html

[AuxBatOn]

Hello,
I have two facts in front me which is contradicting each other. i wish to resolve this confusion.
fact1 - Pressure drops as air gets thicker.
fact2 - air density increases as pressure increases and vice versa.

is any of my fact wrong?
if not, then how come fact1 is correct when its saying when air gets thicker i.e. denser pressure drops?

question2 air shrinks when it gets cold.
Here does shrinking mean denser? if yes.
then fact says temperature is proportional to air density again its a contradiction

Thanks for replying.
Best Regards

When pressure decreases, air gets less dense or gets THINNER.
When pressure increases, air gets denser.
Yes, air gets denser when temperature decreases.

Reference the ideal gas law.

density=Pressure/(temperature * some constant)

[flyingcanuck]

Perhaps you misinterpreted fact 1, where did you read that?

[imcool]

Tutor was dictating and i wrote it. maybe i mis heard fact1
thank you for helping me

[DadoBlade]

Hot air rises, because it is less dense (lighter) than the surrounding air. Hot air balloon come to mind?

Cold air sinks, because it is more dense (heavier) than the surrounding air. Very cold and clear winter days are usually associated with High Pressure systems with corresponding high altimeter settings.

Humidity is also a factor in air density. I've noticed Density Altitude is usually not much of a factor with OAT/surface temperatures of less than ISA (15C).

[digits_]

I've noticed Density Altitude is usually not much of a factor with OAT/surface temperatures of less than ISA (15C).

That's because density altitude is pressure altitude corrected for non-standard temperature. At temperatures below ISA, you will still have a density altitude that can be significantly different from the pressure altitude, just as with hot temperatures. The difference is that temperatures colder than ISA improve performance, so nobody really cares.