warm air rises right?

[fattyjwoods]

i was doing my physics homework (again) and i was wondering (again) if warm air rises shouldn't the sky be warm? say for example, you're flying in a plane and as it gets higher it gets colder and harder to breathe. is there like some kind of wall that stops warm air from rising higher into the atmosphere. I found out that cool air falls-shouldnt that make the ground like freezing? > > >

[insane_alien]

to rise energy has to be expended. this means it will cool as it rises. as it rises, the pressure drops. and it expands it also cools while doing this as well. the reverse happens when it sinks as well.

 

also, most energy is absorbed at the ground and most energy is radiate at some distance above the ground. so you have heating at the bottom and cooling at the top.

 

when you consider the factors involved it then makes sense.

[imp]

i was doing my physics homework (again) and i was wondering (again) if warm air rises shouldn't the sky be warm? say for example, you're flying in a plane and as it gets higher it gets colder and harder to breathe. is there like some kind of wall that stops warm air from rising higher into the atmosphere. I found out that cool air falls-shouldnt that make the ground like freezing? > > >

 

Now, in addition to rising or falling, air contains moisture (water vapor). So, tell us which air you believe to be heavier, moist air containing a lot of water, or dry air, containing no water? imp

[fattyjwoods]

Now, in addition to rising or falling, air contains moisture (water vapor). So, tell us which air you believe to be heavier, moist air containing a lot of water, or dry air, containing no water? imp

 

is it moist air with water, i think>

[imp]

is it moist air with water, i think>

 

1) Look up molecular weights of constituents of water (H2O) and air, N2 and O2, mostly, and think about what addition of water molecules to a given volume of air does to its density.............or,

 

2) Ask any airplane or glider pilot; they will surely know! imp

[insane_alien]

moist air is heavier but as it rises, the moisture condenses out giving up even more heat to the air so it causes further expansion.

[swansont]

moist air is heavier but as it rises, the moisture condenses out giving up even more heat to the air so it causes further expansion.

 

Is it? Water replaces some other molecule of air in a given volume if you have the same pressure and temperature. What molecule can water replace that would make moist air heavier?

[swansont]

"Warm air rises" is shorthand for warm air is less dense, and tends to be replaced by cooler air that is more dense, and a bit more thermodynamics. As i_a noted, look at the energy. More dense on the bottom, less dense at the top minimizes the potential energy.

[fattyjwoods]

shot, thanks i think i get it now