Relief lesson on Rain and RH worksheet

With reference to Figure 1, describe and explain the relationship between relative humidity and air temperature.                                                                                                                                                         [4]

Describe [2m]

-           As temperature increases, the relative humidity within a parcel of air reduces/As the temperature decreases, the relative humidity within a parcel of air increases.

OR there is an inverse relationship between temperature and relative humidity

-         For every 10 deg increase in temperature, relative humidity decreases by roughly 50%

Explain [2m]

-            Warm air has the ability to hold more water vapour

-           Hence as the parcel of air increases in temperature while the amount of absolute water vapour remains the same, there is an overall decrease in the relative humidity/percentage of air saturated by water vapour 

Identify the instrument used to obtain the readings for rainfall in Table 1 and explain where the instrument should be placed in order to get accurate measurements of the daily rainfall.                                                                                                                                                                                       [3]

Instrument = rain gauge (ignore spelling error of ‘guage’) Open grassy area / open field to reduce evaporation as it is cooler in the ground than on a concrete surface. Away from buildings and trees to prevent raindrops from buildings and trees from dripping into the rain gauge or fallen leaves and twigs from choking the funnel [3@1 mark] With reference to Fig. 1, identify the instrument used by the students and state the relative humidity recorded for that day.  Explain how the students obtain this information, using evidence from Fig.1.                                                                                                                                                                           [5]               ·        Instrument used:  wet and dry bulb thermometer (compulsory) ·        Relative humidity recorded: 61% (compulsory) ·        Read/record the dry bulb temperature, which is 33° C ·        Read/record the wet bulb temperature, which is 27° C ·        Find the wet bulb depression is 6° C  [5 @ 1 mark] One student thought that the relative humidity could be related to the depression of wet bulb. State how this relationship could be expressed. [1]                                                                                                    ·        1 mark for ‘the greater the depression of wet bulb, the lower the relative humidity’ or equivalent