the large data set

Question 1

daily mean temperature

Answer 1

in °C – this is the average of the hourly temperature readings during a 24-hour period.

Question 2

daily total rainfall

Answer 2

including solid precipitation such as snow and hail, which is melted before being included in any measurements – amounts less than 0.05 mm are recorded as ‘tr’ or ‘trace’

Question 3

Daily total sunshine

Answer 3

recorded to the nearest tenth of an hour

Question 4

Daily mean wind direction and windspeed

Answer 4

in knots, averaged over 24 hours from midnight to
midnight.
Mean wind directions are given as bearings and as cardinal (compass) directions. The
data for mean windspeed is also categorised according to the Beaufort scale

Question 5

1 knot (kn)=

Answer 5

1.15 mph

Question 6

Daily maximum gust in knots

Answer 6

the highest instantaneous windspeed recorded.
The direction from which the maximum gust
was blowing is also recorded

Question 7

Daily maximum relative humidity

Answer 7

given as a percentage of air saturation with water
vapour. Relative humidities above 95% give
rise to misty and foggy conditions

Question 8

Daily mean cloud cover

Answer 8

measured in ‘oktas’ or eighths of
the sky covered by cloud

Question 9

Daily mean visibility

Answer 9

measured in decametres (Dm). This is the
the greatest horizontal distance at which an object can be seen in daylight

Question 10

Daily mean pressure

Answer 10

measured in
hectopascals (hPa)

Question 11

Any missing data values are
indicated in the large data set as

Answer 11

n/a not available