Wintry Precipitation Terminology...

[AtlanticFlamethrower]

... really confuses me. What's the difference between hail and graupel? Wet snow and sleet? I haven't a clue and I don't think my snow reports are accurate. http://nwstatic.co.uk/forum/public/style_emoticons/<#EMO_DIR#>/cool.gif Having read a lot of googled definitions I'm more confused than ever!! However, I'll post some of my finds for your interest.

While we still have slightly milder conditions the eagle-eyed may be lucky enough to see all the different types!

You don't have to read all the definitions!

There may be better definitions/precipitations type to add that I've not mentioned.

Hail

Precipitation that originates in convective clouds, such as cumulonimbus, in the form of balls or irregular pieces of ice, which comes in different shapes and sizes. Hail is considered to have a diameter of 5 millimeter or more; smaller bits of ice are classified as ice pellets, snow pellets, or graupel. Individual lumps are called hailstones. It is reported as "GR" in an observation and on the METAR. Small hail and/or snow pellets is reported as "GS" in an observation and on the METAR.

www.weather.com/glossary/h.html

Falling ice in roughly round shapes at least 0.2 of an inch in diameter. Hail comes from thunderstorms and is larger than sleet. Hailstones form when upward moving air -- updrafts -- in a thunderstorm keep pieces of graupel from falling. Drops of supercooled water hit and freeze to the graupel, causing it to grow. When the balls of ice become too heavy for the updrafts to continue supporting them, they fall as hailstones. Sleet, in contrast, consists of raindrops that freeze on the way down.

www.usatoday.com/weather/wds8.htm

Precipitation in the form of balls or irregular lumps of ice. Tall cumulonimbus clouds are much warmer at the bottom than at the top. This causes tremendous pressure differences and strong rising air currents, which suck warm water droplets from the bottom of the clouds to the top. There, they freeze. If the currents are strong enough, a hailstone will fall and rise many times, causing several layers of ice to build up until the hailstone is heavy enough to fall from the cloud

www.northcountryweather.com/weather_glossary.html

Hail is a destructive form of precipitation that is 5 to 190 millimeters in diameter. The large downdrafts in mature thunderstorm clouds provide the mechanism for hail formation. Hailstones normally have concentric shells of ice alternating between those with a milky appearance and those that are clear. The milky white shells, containing bubbles and partially melted snowflakes, correspond to a period of rapid freezing, while the clear shells develop as the liquid water freezes much more slowly.

www.geog.ouc.bc.ca/physgeog/physgeoglos/h.html

is precipitation composed of lumps of ice. Hail is produced when large frozen raindrops or other particles in cumulonimbus clouds, grow by accumulating supercooled liquid droplets. Violent updrafts in the cloud carry the particles up through the freezing all; allowing the frozen core to accumulate more ice. when the piece of hail becomes too heavy to be carried by rising air currents, it falls to the ground.

www.met.gov.sb/learn/glossaryfn.htm

Variations in temperature, migration of liquid and vapor water, and pressure of snow cover may result in rounded snow pellets from 2 to 5 mm diameter. Graupel is visually similar to hail, but lacks the banded outward growth pattern of hail.

ebeltz.net/glacglos.html

Graupel See image.

A form of frozen precipitation consisting of snowflakes or ice crystals and supercooled water droplets frozen together.

www.weather.com/glossary/g.html

A type of precipitation that consists of a snow crystal and a raindrop frozen together.

www.geog.ouc.bc.ca/physgeog/physgeoglos/g.html

Small pellets of ice created when supercooled water droplets coat, or rime, a snowflake. The pellets are cloudy or white, not clear like sleet, and often are mistaken for hail.

www.usatoday.com/weather/wwterms.htm

A form of frozen precipitation consisting of snowflakes or ice crystals and supercooled water droplets frozen together. Also known as snow pellets.

www.cagenterprises.com/wx_glossary_g.html

Sleet

partially melted snow (or a mixture of rain and snow)

www.cogsci.princeton.edu/cgi-bin/webwn

Pellets of ice that form when rain or melting snowflakes freeze while falling. (Occurs in cold weather; hail usually occurs in summer.)

asd-www.larc.nasa.gov/asd_over/glossary/w.html

Generally refers to a mixture of rain and snow or falling snow that is melting into rain

www.bom.gov.au/lam/glossary/spagegl.shtml

Rain drops that freeze into ice pellets before reaching the ground. Sleet usually bounces when hitting a surface and does not stick to objects. Forms when snow enters a warm layer of air above the surface and melts and then enters a deep layer of sub-freezing air near the surface and refreezes.

deved.meted.ucar.edu/mesoprim/glossary.htm

Also known as ice pellets, it is winter precipitation in the form of small bits or pellets of ice that rebound after striking the ground or any other hard surface. It is reported as "PE" in an observation and on the METAR.

vwsri.netfirms.com/glossary/s.html

Drops of rain or drizzle that freeze into ice as they fall. They are usually smaller than 0.3 inches in diameter. Official weather observations list sleet as "ice pellets." In some parts of the country "sleet" refers to a mixture of ice pellets and freezing rain.

www.usatoday.com/weather/wds8.htm

Freezing Rain See image.

Rain that falls as liquid and freezes upon impact to form a coating of glaze on the colder ground or other exposed surfaces. It is reported as "FZRA" in an observation and on the METAR.

www.weather.com/glossary/f.html

Rain that turns to ice on impact with the surface.

asd-www.larc.nasa.gov/asd_over/glossary/w.html

Type of precipitation. Occurs when rain hits a cold surface and freeze. For this to occur a surface temperature inversion is required. In such an inversion, the surface must have a temperature below freezing, while the temperature of the atmosphere where the precipitation forms is above freezing. Surface inversions may develop from a variety of causes, but typically they occur near the leading edge of cold air from the north as it pushes southward.

www.geog.ouc.bc.ca/physgeog/physgeoglos/f.html

Snow

precipitation falling from clouds in the form of ice crystals

www.cogsci.princeton.edu/cgi-bin/webwn

Frozen precipitation in the form of white or translucent ice crystals in complex branched hexagonal form. It most often falls from stratiform clouds, but can fall as snow showers from cumuliform ones. It usually appears clustered into snowflakes. It is reported as "SN" in an observation and on the METAR.

vwsri.netfirms.com/glossary/s.html

Type of precipitation that forms in air with temperatures below freezing. Snow forms when water vapor deposits directly as a solid on a deposition nuclei, by passing the liquid state. A snowflake forms first as a very tiny crystal developing on a six-sided hexagonal deposition nuclei. The ice crystal then grows fastest at the six points as these area are more directly exposed to the atmosphere's water vapor. Snow is most common in winter just north of the center of mid-latitude cyclones. As the warm moist air travels around the center of lowest pressure, it overrides colder air located north of the low and is cooled to its saturation temperature, producing rainfall and snow. Snow generally occurs with east winds, since the winds at locations north of a mid-latitude cyclone are from the east.

www.geog.ouc.bc.ca/physgeog/physgeoglos/s.html

Falling ice composed of crystals in complex hexagonal forms. Snow forms mainly when water vapor turns directly to ice without going through the liquid stage, a process called sublimation.

www.usatoday.com/weather/wds8.htm

Snow grain

Very small snow crystals. The ice equivalent of drizzle. [snizzle?]

Thundersnow

A thunderstorm with snow instead of rain falling on the ground.

[thunderstrike]

AtlanticFlamethrower the most constructive post you have ever made

nice done btw!

Did you get that snow in the end?

[Pixel]

brilliant i Now know what i saw today - "Graupel" - loads of it..

excellent post..

[johnholmes]

well posted AF

[Guest Mrs murphymoo]

Thanks for that

Will move it to the snow reports and make it sticky - will hopefully help people identify their wintry precipitation

[Kent Snow]

Top post, very informative indeed.

[Ross B]

No idea why this was locked 2years ago! Anyway, just to add a few extra so the southerners dont report constant whiteouts on thursday http://nwstatic.co.uk/forum/public/style_emoticons/<#EMO_DIR#>/blush.gif

Heavy snow: Snow falling at a rate of 2 cm/hour or more expected for at least two hours. Increased journey times

Minor accidents

Very heavy snow: Snow falling at a rate of 2 cm/hour or more expected for at least two hours, accumulating to 15 cm or more. Local routes impassable

Local loss of power and telecommunication lines

Blizzard: Moderate or heavy snow accompanied by winds of 30 m.p.h. or more, with visibility reduced to 200 m or less; or drifting snow giving rise to similar conditions. Major routes impassable

Local loss of power and telecommunication lines

Severe blizzard :Heavy Snow accompanied by winds of 30 m.p.h. or more, reducing visibility to near zero. Transport infrastructure paralysed

Regional loss of power and communication lines

http://www.metoffice.gov.uk/weather/uk/gui...y_warnings.html

[Phull770]

Have posted more pics of the MidWest USA

http://www.netweather.tv/forum/index.php?s...p;#entry1431464

Peter Hull

[Alternative Ulster]

Is frost precipitation?

[Terminal Moraine]

Is frost precipitation?

Technically no because 'frost' is a generic term to describe an an air temperature lower than 0c. However I'm being pedantic here because I know you're referring to what we all generally describe as frost which is the white rime resulting from the temperature falling below 0c.

Yes it is counted as precipitation as it is water precipitated out of the atmosphere by condensation, due to the fall in temperature, which has then frozen.

Normally it's not enough to register in a rain gauge but occasionally it will do such as if the temperature falls a little below 0c in a moist atmosphere resulting in a thick hoar frost.

[Alternative Ulster]

Thanks. That settles a pub argument. I was right

[alr1970]

Researchers have found 421 words for snow in Scottish dialects.

 

I think my favourtite is â€œskelfâ€, a large snowflake.

[Dorsetbred]

Researchers have found 421 words for snow in Scottish dialects.

 

I think my favourtite is â€œskelfâ€, a large snowflake.

I'd like to know how many of the 421 are used in the Scottish regional discussion thread!