Minimum Temperature
The minimum thermometer records the lowest
temperature since last reset. This usually occurs in the early
hours and so is attributed to the day of reading.
Grass Minimum Temperature
This is a minimum thermometer with a black anti-condensation
shield and records the minimum temperature at night on the grass.
The thermometer is placed on the ground in a frame so that the
thermometer just touches the tops of the blades of grass.
Concrete Minimum Temperature
This is a minimum thermometer
identical to the one that measures the grass minimum. It
is placed lying on a piece of concrete and records the
minimum temperature of the concrete.
Soil Temperature (100cm)
This thermometer is attached to a chain and sits
at the bottom of a tube which is 1m deep. The thermometer is read
at 0900 and the present temperature recorded.
State of Ground
A patch of bare earth is maintained within the
weather station and its condition compared with one of the two
tables reproduced below. One without snow and one with snow. One
or other is used never the two on the same day.
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CODED FOR STATE OF GROUND
WITHOUT SNOW
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CODED ENTRY
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CODED FOR STATE OF GROUND
WITH SNOW
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Surface of ground dry
(without cracks and no appreciable amount of dust or loose
sand)
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0
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Ground
predominantly covered by ice
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Surface of
ground moist
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1
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Compact or
wet snow (with or without ice) covering less than one-half
of the ground
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Surface of
ground wet (standing water in small or large pools on the
surface)
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2
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Compact or
wet snow (with or without ice) covering at least one-half
of the ground but ground not completely covered
|
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Ground
flooded
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3
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Even layer
of compact or wet snow covering the ground completely
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Surface of
ground frozen
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4
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Uneven
layer of compact or wet snow covering the ground
completely
|
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Glaze on
ground
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5
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Loose snow
covering at least one-half of the ground
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Loose dry
dust or sand not covering the ground completely
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6
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Loose snow
covering at least one-half of the ground (but not
completely)
|
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Thin cover
of loose or dry dust or sand covering the ground
completely
|
7
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Even layer
of loose dry snow covering the ground completely
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Moderate
or thick cover of loose dry dust or sand covering the
ground completely
|
8
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Uneven
layer of loose dry snow covering the ground completely
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Extremely
dry with cracks
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9
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Snow
covering the ground completely, deep drifts
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Snow Depth
Snow depth is only measured and entered
if snow grains, hail or ice
pellets are covering half the ground or more. It is measured
to the nearest whole centimetre with any measurement of 0.5
centimetres being thrown up. (2.5 centimetres is entered as 3).
Rainfall
Rainfall is the total amount of precipitation measured at 0900 GMT
in millimetres and tenths. The rainfall total covers a 24 hour
period, from 0900 ‘yesterday’ to 0900 ‘today’. As more of the
rainfall is recorded prior to midnight the reading is applied to
the previous day.
Sunshine
Sunshine is entered in hours and tenths. This figure will be for
the period sunrise to sunset and should be entered against the
date on which it occurred.
As the card is changed in the afternoon at 1600 the sunshine
record will be on two cards, yesterday’s card between dawn and
1600 and today’s card 1600 to dusk.
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