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WORKSHEET 21Activity - Wet AirPrint and copy this worksheet for use in the classroom. |
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Purpose
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Equipment
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SafetyHandle thermometers carefully. Students shouldn't try to clean up the mess if a thermometer happens to break. Use a mercury spill-kit or throw sulphur over the mercury and clean it up wearing gloves and using a brush and pan. Remember not to touch it because mercury is a poisonous metal.
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Procedure
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Questions
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ExplanationHumidity is a measure of the amount of water vapour in air. If air temperature is 20°C, each cubic metre of air can contain up to 17g of water vapour. If there is only 8.5g of water vapour per cubic metre at 20°C, we can say the relative humidity is 50% Humidity can have a strong influence on how comfortable we feel. Combinations of high temperature and high humidity can be very uncomfortable. Physical activity and exposure to direct sunlight can also increase heat stress. |
Humidity ChartThe
numbers on the side of the chart represent the dry-bulb temperature.
The numbers at the top represent the difference between the
dry and wet bulb temperature. Measurements are in °C. The
point at which the row and the column intersects is the percentage humidity
in the air. For example, if the dry bulb temperature is 20°C, and
the wet bulb depression is 5.5°C, then the humidity is 55 percent.
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0.5
1 1.5 2 2.5
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3_
3.5 4 4.5 _5
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5.5 6 6.5 7 7.5 | 8_ 8.5 9 9.5 10 | 11 12 13 14 15 16 | |
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40 39 38 37 36 |
97 94 91 88 85 97 94 91 88 85 97 94 91 87 85 97 94 91 87 85 97 94 90 87 84 |
82 80 77 74 72 82 79 77 74 71 82 79 76 74 71 82 79 76 73 70 81 78 76 73 70 |
69 67 64 62 60 69 66 64 61 59 68 66 63 61 58 68 65 63 60 58 67 65 62 60 57 |
57 55 53 51 48 57 54 52 50 48 56 54 51 49 47 55 53 51 48 46 55 52 50 48 45 |
44 40 37 33 29 26 44 40 36 32 28 25 43 39 35 31 27 24 42 38 34 30 26 23 41 37 33 29 25 21 |
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35 34 33 32 31 |
97 93 90 87 84 97 93 90 86 84 97 93 90 86 83 97 93 90 86 83 96 93 90 86 83 |
81 78 75 72 70 81 78 7572 69 80 77 74 71 69 80 77 74 71 68 80 77 73 70 67 |
67 64 61 59 56 66 64 61 58 56 66 63 60 58 56 66 62 60 57 54 64 62 59 56 53 |
54 51 49 47 44 53 51 48 46 44 52 50 47 45 43 52 49 46 44 42 51 48 45 43 41 |
40 36 32 28 24 20 39 35 30 26 23 19 38 34 29 25 21 16 37 32 28 24 20 16 36 31 27 22 18 14 |
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30 29 28 27 26 |
96 93 89 86 83 96 93 89 86 82 96 93 89 85 82 96 92 88 85 82 96 92 88 85 81 |
79 76 73 70 67 79 76 72 69 66 79 75 72 69 65 78 75 71 68 65 78 74 71 67 64 |
64 61 58 55 52 63 60 57 54 52 62 59 56 53 51 62 59 56 52 50 61 58 55 51 49 |
50 47 44 42 39 49 46 43 41 38 48 45 42 40 37 47 44 41 38 36 46 43 40 37 34 |
34 30 25 21 17 13 33 28 24 19 15 11 32 27 22 18 13 _9 30 25 21 16 11 _7 29 24 19 14 _9 _5 |
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25 24 23 22 21 |
96 92 88 84 81 96 92 88 84 80 96 92 88 84 80 96 92 87 83 79 96 91 87 83 79 |
77 74 70 67 63 77 73 69 66 62 76 72 69 65 62 76 72 68 64 61 75 71 67 63 60 |
60 57 54 50 47 59 56 52 49 46 58 55 51 48 45 57 54 50 47 44 56 52 49 46 42 |
44 41 38 36 33 43 40 37 34 31 42 39 36 33 30 40 39 36 33 30 39 35 32 29 26 |
27 22 17 12 _7 _3 26 21 15 10 _5 24 18 13 _8 _3 22 16 11 _5 20 14 _8 _3 |
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20 19 18 17 16 |
96 91 87 83 78 95 91 86 82 78 95 91 86 81 77 95 90 86 81 77 95 90 85 81 76 |
74 70 66 62 59 74 70 65 61 58 73 69 65 60 56 72 68 64 59 55 71 67 62 58 54 |
55 51 48 44 41 54 50 46 43 39 52 49 45 41 37 51 47 43 39 35 50 46 41 37 34 |
37 34 30 27 24 35 32 29 25 22 34 30 27 23 20 32 2824 21 17 30 26 22 18 15 |
18 12 _6 15 _9_3 13 _7 10 _4 _8 _1 |
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15 14 13 12 11 10 |
95 90 85 80 75 95 90 84 79 74 95 89 84 79 74 94 89 83 78 73 94 88 83 77 72 94 88 82 77 71 |
71 66 61 57 52 70 65 60 56 51 69 64 59 54 49 68 63 57 53 48 66 61 56 51 46 65 60 54 49 44 |
48 44 40 36 31 47 42 38 33 29 45 40 36 31 27 43 38 34 29 24 41 36 31 26 22 29 34 29 24 19 |
27 24 20 16 12 25 21 17 14 _9 23 18 14 10 _6 20 16 11 _7 _3 17 13 _8 _4 14 _9 _5 |
_5 _2 |
Extension ActivitiesHow is humidity related to weather conditions? Design an experiment to use wool to measure humidity. Test the experiment by comparing your measurements with the wool to humidity measurements from meteorological instruments.
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Fact fileCows lying down, appearance of large numbers of frogs and snails, wool swelling and straightening, pine cone scales becoming pliable, and your hair getting longer: theses may all be signs of high humidity. |
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This
activity is courtesy of
the Cooperative Research Centre for Southern Hemisphere Meteorology |
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