‘Prent weather’reprents the weather conditions at the time of obrvation,coded as two figures.Codes range from 00to 99,with the higher figures being more significant (except 17,which takes precedence over the range 20to 49).The following notes will help you decide which code to u for prent weather.
Codes 50to 99are ud when precipitation is falling at your station at the time of obrvation.Codes 00to 49are ud when precipitation is not falling at your station at the time of obrvation.The ranges of codes are then split into smaller groups of similar weather types.
我要射啦Note:Remember to u the weather diary,the comments option on SAMOS or the SYNOP coded message for reporting special phenomena.
Prent weather
Precipitation falling at the time of obrvation 80–99All types of showers,or any type of precipitation
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associated with current and recent thunderstorms 70–79Solid (i.e.frozen)precipitation (mainly snow)that
has not fallen in the form of showers 68–69Mixture of solid and liquid precipitation (rain,
drizzle,snow)50–67Liquid precipitation (drizzle and/or rain)
No precipitation falling at the time of obrvation 40–49Fog
30–39Phenomena other than fog affecting visibility,such
as blowing or drifting snow 20–29Weather not occurring at the time of obrvation
but in the previous hour 00–19Other weather phenomena,of varying
significance,not included in the groups above
Version 4.Amended December 2009
Definitions
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At the station—where the obrvation is normally made.
At the time of obrvation—obrvation time to the nearest minute.
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Distant/at a distance/within sight—phenomenon being obrved is not at your station.
Recent/in past hour/during past hour—phenomenon not occurring at time of obrvation but at some time during past hour.
kevin hartContinuous precipitation—precipitation falling for
1hour or more.
Intermittent precipitation—precipitation which hasn't fallen continuously for1hour or more.
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Visibility at the station—defined as the greatest horizontal distance at which an object can be recognid in daylight(when visibility varies in different directions, the visibility at the station is to be taken as the lowest value).
Prent weather descriptions Precipitation—rain,drizzle,snow,hail,snow pellets, snow grains,ice pelle
ts,small hail,diamond dust and any combination of the falling from the sky.Therefore, drifting snow and blowing snow are not included.Showers—precipitation falling from convective cloud (i.e Cumulus or Cumulonimbus clouds).Showers tend to start and stop abruptly,they are often characterid by large variations in intensity over short periods of time and the raindrops tend to be larger than in non-showery precipitation.
Rain/drizzle—drizzle often appears to float in the air and the drops make no effect on puddles,whereas raindrops create rings as they hit the puddle surface. Freezing precipitation—rain or drizzle that freezes on impact with the ground(it is liquid as it falls,turning to ice immediately on impact,forming a clear coating of ice on roads,twigs,overhead wires,etc.).This coating is called‘glaze’or,commonly,‘black ice’.
Frozen precipitation—precipitation that is already ice before it reaches the snow,hail,small hail, ice pellets,snow pellets,snow grains and diamond dust).To decide what is falling,consider the appearance, size and clouds of origin.罗列的近义词
Mixed precipitation—two or more types of precipitation falling together.
Snow—ice crystals that appear white(isolated star-like crystals and small flakes occur in colder weat
her, whereas large wet flakes are typical around0°C).
Snow grains—appear like small grains of rice,usually falling in small quantities over short periods;when they fall on hard ground,they do not bounce or break up (grains fall from stratus,or even fog,but never in the form of a shower).
Hail—transparent or opaque,spherical or irregular; main distinguishing feature is its size;diameters start at about5mm(always falls from very deep convective clouds,so is often associated with thunderstorms). Small hail—typically diameters of2to5mm,more or less spherical and mi-transparent,though can be transparent(only falls from shower clouds,including thunderstorms;bounces with an audible sound when it falls on hard ground and is not easily crushed).
普林斯顿大学公开课Snow pellets—usually rounded,white and opaque, having diameters of2to5mm;looking like tiny snow balls(usually fall from shower clouds,accompanied by rain or snow but—unlike small hail—they usually break up on impact,being brittle and easily crushed).
Ice pellets—spherical or irregular ice particles that are transparent,with diameters up to5mm.They are not easily crushed,bounce with an audible sound on impact and usually fall from altostratus or nimbostratus clouds.Diamond dust—tiny ice crystals only visible when they glitter in the sunshine;falling from a clear sky;rarely experienced in UK.
Fog—tiny water droplets suspended in air,reducing the visibility below1,000m in ANY direction with the fog being at least2m deep above the ground;the relative humidity is100%(or very nearly so)and the air usually feels clammy and raw(can be described as CONTINUOUS or occurring in PATCHES).Note:If,during the day,cloud or blue sky can be en through the fog or,at night,stars are visible,then the sky is said to be visible.If,due to thick fog or heavy precipitation(usually snowfall),the sky,stars or cloud cannot be en,then
‘sky not visible’applies.
Mist—visibility1,000m or more but usually less than 10km,and relative humidity greater than about95%. Rime—tiny fog droplets may freeze when they come into contact with objects like posts and twigs and,when this happens,a deposit of‘rime’ice gradually builds up on the windward side(in very cold weather,and with light winds or calm,rime can accumulate on all surfaces of objects,not just the windward side).
Ice fog—tiny ice particles suspended in the air at very low temperatures,unlikely to be experienced in UK.
Shallow fog—not higher than about2m;visibility below this height must be less than1,000m,but above this height is1,000m or more.
Haze/smoke/dust—tiny dry particles suspended in the air,such as smoke or industrial pollution,which reduces visibility.
Drifting/blowing snow—both conditions satisfied by snow that has fallen to the ground and is then raid by strong winds;however,only blowing snow riously affects the visibility at eye level(heavy blowing snow will verely affect both vertical and horizontal visibility; heavy drifting snow will verely affect the horizontal visibility below eye level).
Drifting/blowing sand/dust,sandstorm/duststorm, sand/dust whirls—are well-developed features, unlikely to be experienced in the UK. Thunderstorm—always report a single rumble of thunder,even if the thunderstorm is obviously a considerable distance away.Funnel cloud—forms from cumulonim
bus, characterid by rapid rotation and a downward extension of the dark cloud ba towards the ground, often with loo material and debris raid and flung out of the circulation(if the associated inten wind circulation reaches the ground,the phenomena becomes a tornado—the huge convective clouds that produce the phenomena always have dark,ragged bas).
英语b级考试试题Squall—occurs when the mean wind speed increas suddenly by at least16kn(3Beaufort forces)to a new mean of at least22kn(Beaufort force6),and the increa lasts for at least one minute.Squalls are usually associated with thunderstorms and active cold fronts. Like funnel clouds,squalls are not reported as often as they might be becau precipitation is often falling at the same time and this warrants the u of a higher code figure.
When you obrve mixed precipitation,report the highest intensity.For example:
Heavy rain falling with moderate snow—report as heavy;
runtimeShower consisting of moderate rain and slight hail—report as moderate.
