00:03
Hello students, in this question we have a parcel of air with temperature of 70 degrees fahrenheit and the dew point temperature which is 48 degrees fahrenheit.
00:17
So is the relative humidity of the parcel 100 percent? the relative humidity is not 100 percent.
00:23
First question, no.
00:26
Relative humidity is the ratio of actual amount of water vapor, amount of water vapor in the air to the maximum amount of water vapor.
00:42
So that is the relative humidity.
00:45
So the dew point temperature of 48 degrees indicates that the air is saturated with water vapor and cannot hold any more water vapor at the temperature.
00:56
So the actual amount of water vapor in air may be less than the maximum amount it can hold which results in a lower relative humidity.
01:06
Okay, so that's the first thing.
01:09
Now second thing is, second question is, what if the air is forced upward by a mountain range? will it cool at the dry or most adiabatic rate until it reaches condensation level? so when the air is forced upward a mountain range, right, when it goes up, so it will cool at the most adiabatic rate until it reaches the condensation level.
01:34
So when it reaches condensation level, it condenses.
01:37
The moist adiabatic rate is the rate at which the saturated air cools as it rises and expands due to decreasing pressure.
01:47
This rate is lower than dry adiabatic rate because some of the heat released by the air as it rises is used to condense water vapor into liquid droplets.
01:58
So this then releases latent heat that helps to slow the cooling air.
02:04
So therefore the air is already saturated at the surface, it will cool at the most adiabatic rate as it rises and expands.
02:12
This will lead to the formation of clouds and precipitation when it reaches the level.
02:19
It could become snow if it is too like the height is too enough.
02:26
So that is the second question.
02:29
Okay, now the third question is, what is the condensation level or altitude of this air parcel? explain how we can do it.
02:40
So to find the condensation level of the air parcel, we need to determine the height at which the air temperature cools down to dew point temperature.
02:49
This is known as lcl, right, lifting condensation level.
02:54
So lifting condensation level is the height at which the air temperature cools to the dew point.
03:02
So lcl, we can calculate lcl as equal to, lcl will be equal to t minus td times 1000 divided by 4 .4.
03:14
So this is lcl equation...