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B) Relative and Absolute Humidity Remember that relative humidity can be describ

ID: 113353 • Letter: B

Question

B) Relative and Absolute Humidity Remember that relative humidity can be described as the amount of water in a parcel of air (vapor pressure) relative to the amount of water that parcel of air can hold (saturated vapor pressure), which varies with temperature (A). Relative humidity (RH) can be calculated directly from; RH = 4x100 where ea vapor pressure of air (mb) and es saturated vapor pressure (mb). Note that the same equation can be rearranged so that; RH e, =box 100 and d 100 RH Complete the empty boxes in the table below. Use the graph in A to determine es and the existing data and equations above to calculate ea or RH. Once completed, answer the questions below Tair (°C) -25 16 32 32 | es (mb) | ea (mb) 0.5 | RH(%) Location Antarctic ice-sheet San Francisco in summer Phoenix AR in summer Amazon Basin 100 12.5 38.9

Explanation / Answer

Relative humidity= ea/es *100

For Antartic ice sheet

Given: Tair( degree celsius)=-25 degree celsius

es(mb)=?

ea(mb)=0.5

RH(%)=?

First we need to calculate es( saturated vapour pressure)

Formula for calculating saturated vapour pressure Es=6.11*10*7.5*Tc)/237.7+Tc)

es=6.11*10*(7.5*(-25)/237.7+(-25)

es=61.1*(-187.5)/(212.7)

es=61.1*0.88

es=53.76 mb

Now RH%=ea/es*100

RH%=0.5/ 53.76*100

RH=0.93%

San Francisco in summer

Given Tc=16 degree celsius

RH %=100

es=?

ea=?

es=6.11*10*(7.5*(16)/237.7+16)

es=61.1*120/253.7

es=61.1*0.47

es=28.7

Now ea=RH/100*es

ea=100/100*28.7

ea=28.7 mb

Phoneix AR in summer

Given: Tair( degree celsius)=32

ea=12.5 mb

es=?

es=6.11*10*(7.5*32)/237.7+32)

es=61.1*(240/269.7)

es=61.1*0.88

es=53.76

Now RH%=ea/es*100

RH%=12.5/53.76*100

RH%=23.35

For Amazon Basin

Given: Tair( degree celsius)=32

ea(mb)=38.9

es(mb)=?

RH%=?

es=6.11*10*(7.5*32/237.7+32)

es=61.1*(240/269.7)

es=61.1*0.88

es=53.7

Now RH%=ea/es*100

RH%=38.9/53.7*100

RH%=0.72*100

RH%=72.4