0:01
humidity is often featured in weather forecast
0:04
as in humidex numbers or just a percentage amount for relative humidity
0:09
and is also important in
0:12
building science as in equilibrium moisture content
0:16
also heating ventilation air conditioning for occupied call
0:20
part because of the way humans
0:23
cool themselves just the human body and it has to do with heat loss
0:28
so humidity is fairly straightforward
0:32
and I'll explain what so relative about it humidity is just what a vapor or
0:36
moisture in the air
0:38
and his water bowl here know someone to and you can see it
0:41
compensating neatly all around everywhere
0:45
at a given temperature liquid water
0:49
evaporates and loses some like yours
0:53
into the guess above it it doesn't have to be air necessarily
0:57
water at any temperature liquid water
1:01
at any temperature will have are
1:04
vapor pressure and will evaporate some
1:08
of its some with scar mass
1:13
and will centuries well deeper if it's a closed vessel and it was such a great
1:18
day
1:19
gas in this case air above it long
1:23
months is monthly guess above is saturated condensates
1:27
and there this is called do point and youth
1:31
as in and that's only this way do
1:34
point they Cassie their dewpoint dewpoint
1:39
don't have anything to do with cold or not necessarily
1:43
this is the middle of summer you can see these droplets beautifully for me so
1:48
however it does form in the morning
1:51
do forms typically in the morning and then the Sun rises up so
1:55
as with any gas
1:58
because we're dealing with gas is here ima in a given volume
2:02
guesses are in data related to changes in temperature and pressure so
2:09
I'm gonna get back to the morning you first
2:12
what's a relative about humanity because
2:16
this water vapor and is given volume
2:20
in a guess about it is a pressure related
2:25
let people pressure pressure related how much
2:28
I'll war how much water vapor
2:32
not steam but not necessarily steam
2:36
steam is just hot water vapor so how much water vapor
2:39
this give I'm gaskin containing
2:42
it has to do with the pressure
2:45
alva a vapor so
2:49
I don't know I'm gonna go VP vapor pressure
2:52
and its
2:55
being divided or related do the
2:58
on the
3:02
vapor pressure at the point where it's
3:05
situated son is almost set saturated and missus
3:09
the CD actua the actual divided by the
3:13
amount that can be the can be
3:17
at saturated situation where it's at dewpoint
3:21
and had to get a percentage this time the 100
3:24
so for example if the up
3:28
pressure it inside the vapor pressure is
3:31
and 30 and the maximum
3:34
paper pressure can be I'm just gonna go easy on the numbers 100
3:39
so 30 or 100 thats 30 percent
3:42
yesterday over 100 years zero-point 3
3:46
and 0.3 times to be there is your thirty percent I'm gonna write it here
3:50
so let's thank you expect semantically
3:54
now because this water vapor
3:59
is in a gas in this case
4:02
your we'd guess is everything is temperature and pressure related letter
4:06
said
4:07
and if the temperature goes up 002 here
4:10
if the temperature goes up the relative relative humidity percentage drops down
4:15
that's because this is a fraction and and it's half actions
4:19
here the temperature goes up the same amount of moisture that
4:23
gonna see at zero degrees are
4:26
a small amount of are moisture is in the air
4:30
and its vapor pressure the small
4:33
if the temperature runs up the the
4:37
did or whatever amount was previously saturating
4:41
and compensating following do you or
4:45
droplets of liquid water on the silos is now at a higher temperature
4:51
not nearly enough to be
4:54
to represent the saturated amount so the relative humidity
4:58
in your relative to its saturated state
5:02
it drops down and because and
5:05
with pressure goes the other way around pressure good if temperature
5:09
drops them relative humidity goes up if pressure goes up
5:12
as im the waterway for being squeezed our
5:16
up the volume of gas above it
5:19
their relative humidity goes of because it can contain
5:23
at the pressure less work may pour les
5:26
3 bopping around water molecules
5:31
than then at a lower pressure
5:34
so a relative humidity is important
5:38
and that's basically what the numbers mean that humanity is not so easy to
5:42
measure
5:44
and not so easy to calculate complicated equations for it
5:48
but that's basically the concept it's a it's a balance
5:52
of the amount lets a floating
5:56
%um the air or guess above a body of water
6:01
and it has to do with the way temperature and pressure