(a) Name the instruments used in measuring the following: (i) Rainfall; (ii) Humidity (iii) Temperature (iv) Wind. (b) With the aid of a diagram, describe t...
Question 1 Report
(a) Name the instruments used in measuring the following:
(i) Rainfall; (ii) Humidity (iii) Temperature (iv) Wind.
(b) With the aid of a diagram, describe the instrument used to measure rainfall.
(c) Explain how the instrument described in (b) above is used.
Answer Details
(a) Instruments used for measurement
| Weather element | Instrument |
|---|---|
| (i) Rainfall | Rain gauge |
| (ii) Humidity | Hygrometer, or wet-and-dry bulb thermometer |
| (iii) Temperature | Thermometer, especially the maximum and minimum thermometer |
| (iv) Wind | Wind vane for direction and cup anemometer for speed |
(b) Rain gauge
A rain gauge measures the depth of rain received at a place during a stated period. It consists of a cylindrical outer metal case, a funnel of standard diameter fitted at its top, and an inner collecting bottle. Rain passing through the funnel is stored in the bottle. The collected water is measured with a graduated measuring cylinder marked in millimetres.
(c) How the rain gauge is used
- The gauge is installed in an open, level site away from trees, walls and buildings. Its rim is about 30 cm above the ground to prevent splash water from entering it.
- Rain falls into the funnel and is channelled into the inner collecting bottle.
- At a fixed time each day, usually 9.00 a.m., the bottle is removed and the collected water is poured into the graduated measuring cylinder.
- The water level is read in millimetres. This gives the rainfall received during the preceding 24 hours.
- The bottle is emptied, replaced in the outer case and left to collect the next day's rainfall. Daily totals may be added to obtain monthly and annual rainfall totals.
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