How to Collect Weather Observations (PDF)

Preparation

Equipment

To collect the weather observations for cloud cover, wind direction and speed, weather conditions and air temperature the following equipment will be required:

  • Compass (measuring in °)
  • Anemometer* (measuring in mph, km/h or m/s)
  • Thermometer (measuring in °C)
  • Calculator

*An anemometer is not crucial as observations can be taken visually using the Beaufort Scale.

Site Selection

Choose a safe location away from roads or car parks within your school site which you have permission to use when you will be taking observations. Try to choose a site which is not close to buildings or metalled surfaces and not in the shelter of hedges or walls. For the most reliable and accurate readings an open grass surface is recommended. Select the site before taking observations and ensure all readings are taken at the same site.

Collecting Weather Observations

It is recommended that the following table is printed or copied and used to record the weather observations in the field, before submitting the observations via WOW. Detailed instructions are provided below.

Weather Observation Card
VariableObservation
Time (hh:mm)
Date (dd/mm/yyyy)
Local Weather Summary (Code)
Total Cloud Cover (Oktas)
Wind direction (Compass Scale)
Wind speed (mph or Beaufort Scale) Reading 1:  
Reading 2:  
Reading 3:  

Mean:  


Air Temperature (°C)

Weather Observation Variables

Cloud Cover

This is measured using the Okta scale where the proportion of cloud covering the sky in eighths is observed and the suitable value from the scale is recorded.

Cloud Cover
OktasCloud Cover
0No cloud visible
1Sky 1/8 cloudy
2Sky 1/4 cloudy
3Sky 3/8 cloudy
4Sky 1/2 cloudy
5Sky 5/8 cloudy
6Sky 3/4 cloudy
7Sky 7/8 cloudy
8Sky completely obscured
9Dense Fog

Wind Direction (compass required)

Orient yourself such that the wind is blowing directly towards you. Then holding a compass level rotate the scale so that 0° aligns with the North arrow and record the direction you are facing in degrees. Convert this direction from degrees to the nearest point on the 16-point compass scale.

Wind Speed
ForceLocal Effect
0Calm
1Slight movement of air
2Wind felt on face, leaves rustle
3Leaves constantly moving
4Small branches moving
5Small trees begin to sway
6Large branches moving
7Large trees sway
8Small branches break off trees
9Slight structural damage
10Trees uprooted
11Widespread structural damage
12Hurricane force

Wind Speed (anemometer* and calculator required)

Recording in mph, km/h or m/s

Hold the anemometer at arm's length at approximately 1.5m above ground level. Take 3 readings separated by 30 seconds and calculate the mean wind speed from these three readings. If necessary, convert this wind speed into mph using the conversion 1mile = 1.609km and 1km = 1000m and record this final figure.


Recording using Beaufort Scale

Observe the effect of the current wind on local trees and buildings; record the suitable force from the Beaufort Scale.

Local Weather Summary

Observe the current weather conditions and record the code which best describes the weather:

Local Weather Summary
CodeWeather Conditions
100Cloudless sky (day)
111Cloudless sky (night)
101Some clouds in sky (day)
112Some clouds in sky (night)
102Total cloud covered sky
103Foggy now
104Raining now
105Raining in last hour
106Snowing now
107Not snowing, snow on ground
113Snowing now, snow on ground
108Hail
109Thunderstorm
110Frosty now

Air Temperature (thermometer required)

Hold the thermometer (not at the bulb if an analogue thermometer is used) at arm's length at approximately 1.5m above the ground level. Ensure the thermometer is in the shade; use your shadow if there is no local shade. Record the stable temperature after 1 minute.

Local Weather Summary Image

Cloud Cover Image

Ice Image

Alexander Todd & David Leppla-Weber (University of Exeter)
Supported by EPSRC and CliMathNet