Extract from the weather journal

Recording weather observations

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Time: It's important to adopt a standard time for observations. Official readings are taken every three hours, but you can choose any time. Some people take readings at 9am, before leaving for work. But whatever it is, keep to it each day.

Pressure: Your barometer must be adjusted to record the equivalent of mean sea-level pressure. Most aneroid barometers have an adjustment screw for this purpose. Advice on calibration can be obtained from the Bureau office nearest you.

Temperature: Mercury thermometers or electronic sensors must be correctly placed, or exposed. Temperatures are generally recorded at standard times, such as 9am and 3pm.

Humidity: Measurements can be taken from a suitably exposed hair hygrometer or electronic sensor. Alternatively, a simple estimate can be made based on physical comfort (i.e. low, medium, high humidity). Take care to distinguish between a hot, sultry summer's day with a high level of physical discomfort (80 per cent relative humidity) and a cool winter's day (also 80 per cent humidity). Physical discomfort is often related to temperature rather than humidity.

Wind: Record both wind speed and direction. Direction can be recorded as one of 16 points on the compass (NNW,NNE, etc.) or as one of eight points (N, NE, NW, etc). Wind speed can be recorded in kilometres per hour, metres per second, or knots. But be consistent.

Cloud: The important aspects to note are the amount of sky covered by cloud (e.g. eight oktas) and the individual cloud types or broad groupings (e.g. 318 stratus or 318 low). Another element of interest is the direction the clouds are moving. Record this in the "comments" column.

Rain: Record rainfall (in millimetres) collected in a simple rain gauge over a given period - generally the 24 hours to 9am. The amount is recorded under the day the reading is taken. Enter yes/no in the "rain day" column to indicate whether rain fell.