field work Flashcards
(13 cards)
1
Q
temperature
A
maximum & minimum thermometer
2
Q
wind speed
A
anemometer
3
Q
wind direction
A
wind vane
4
Q
atmospheric pressure
A
barometer
5
Q
relative humidity
A
sling psychrometer
6
Q
rainfall
A
rain gauge
7
Q
anemometer data collection
A
- Stand in an open area where wind flows freely
2. Hold it up high & read of the display on the anemometer
8
Q
wind vane data collection
A
- Place the wind vane where the is blowing directly at it
- Hold it in an open area, away from you & slightly above your head & ensure that there is no obstruction
- Use a compass to determine where is north
- Turn the wind vane so that the direction mark labelled N matches with the compass arrow pointing north
- Record direction the wind vane points to, this is the direction the wind is blowing from
9
Q
precaution for wind vane
A
take the readings in an open area to prevent tall buildings, trees or humans from affecting accuracy of the readings
10
Q
maximum & minimum thermometer data collection
A
- Before a new max. & min. reading can be taken, the thermometer must be reset
- Hold it above the ground & away from your body. After 1 minute take the reading. The lowest point of each index indicates the temperature
Note that temperature is affected by the amount of shade, wind & the type of ground e.g. concrete/grass
11
Q
maximum & minimum thermometer precautions
A
- Thermometer should not have contact with ground or warmed objects, 1.5m above the ground & at arm’s length so that body heat/heated surfaces does not interfere with the measurement
- Thermometer should not be placed under direct sunlight to ensure we measure air temperature, not solar radiation
- Temperature should be recorded at the same time throughout the fieldwork to ensure accuracy as temperature varies throughout the day
- Take readings at eye level to avoid parallex error
- Take at least 3 readings to take average & reduce error
12
Q
sling psychrometer data collection
A
- Wet the wick of the wet bulb thermometer with distilled water
- Swing it at a steady pace, & keep it away from your body
- After 1 minute, read & record the temperature on the wet thermometer
- Repeat step 2 & swing it & record the temperature on the wet bulb again
- If the 2 temperatures recorded are different, tepee at steps 2 to 4 again until same temperature is recorded consecutively
- Calculate wet bulb depression, the difference between the wet & dry bunks temperature
- Use the conversion table, & obtain R.H. finding the value where the wet bulb depression intersects with the dry bulb temperature
13
Q
sling psychrometer precautions
A
- Should be swung at a constant pace so that the wet bulb temperature reading will be accurate
- Take readings at eye level, to reduce parallax error
- Take at least 3 readings to take average & reduce error
