gi instruments

Question 1

rain gauge

Answer 1

1) find an appropriate spot to place rain gauge: open area where it is not close to buildings and trees and where there is protection from the wind since win may blow the rain past the rain gauge, leading to an underestimation of rainfall
2) place rain gauge underground with 30 cm protruding above ground to prevent it from falling over. the 30cm protruding above is to prevent rain from splashing, which may result in inaccurate readings

Question 2

anemometer

Answer 2

1) hold anemometer at an open area where wind flows freely

2) read off the display

Question 3

wind vane

Answer 3

1) place at an open area where wind blows directly at it
2) use a compass to determine how wind vane should be positioned. Turn wind vane so that its direction mark labelled ‘N’ matches with the compass arrow pointing north
3) record direction wind vane points to. this is the direction wind is coming from.

Question 4

wind rose

Answer 4

( not an instrument but to present data)
to read:

1) rectangles point in the direction the wind is coming from
2) number in boxes represent the dates in a month which the wind blew from that particular direction
3) no in circle shows the number of calm days

Question 5

barometer

Answer 5

air pressure
measured in millibars (mb)

1) check that the moveable pointer is arranged over the measuring hand to mark the current pressure
2) the measuring hand moves according toair pressure. moves to left→drop in air pressure moves to right→increase in air pressure

Question 6

max min temp

Answer 6

1) lowest point of each metal index indicates temp

2) diff between the two temps is the diurnal temperature range

Question 7

stevenson screen

Answer 7

• max min them placed inside to keep it out of sunlight
• to elevate thermometer above the ground→ground absorbs heat, placing them directly on the ground will result in inaccurate readings

Question 8

sling psychrometer

Answer 8

1) dip the wick of the wet bulb therm in water
2) swing sling psychometer at a steady and comfortable pace while keeping it far from body so that it does not pick up on body heat
3) water evaporates from the wick as the sling psychometer is swung
4) after a minute, record the temp of the wet bulb them
5) continue swinging for another minute and record the temp again
6) if the temperature recorded is different, keep swinging and recording with and interval of 1 min until same temp is recorded consecutively
7) read and record temp on dry bulb therm
8) calc difference between wet bulb and dry bulb, which is called the wet bulb depression
9) refer to conversion table to find out rh