Precipitation type - newly added


  • administrators

    Replying to: When will precipitation type be added?

    @Philly2034 @Ken

    Hi, we have just launched the "Precipitation type" layer (Rain, Freezing rain, Mixed ice, Snow, Wet snow, Rain with snow, Ice pellets).

    Cheers, Marie


  • Moderator

    What does Ice pellets mean? Is it hail?


  • Moderator

    My guess is having lived in a northern part of the US in the past, we called it sleet. The difference is raindrops fall but freeze before hitting the ground. Hail bounces around up in the air adding layer and layers. Sleet is a cold weather issue and hail is a warm weather issue.



  • @tomber42
    Smaller than hailstones. Less than 5 mm in diameter.


  • Moderator

    Also, sleet tends to be softer pellets where hail is frozen rock hard.


  • Moderator

    Ahh.. Ok, now I know.. in German. we say Graupel


  • administrators

    Hi @Tomber42 , it's different. We don't actually have a "hail" icon nor a layer for it. Hail normally occurs in rainstorm or thunderstorm, and is the result of strong updrafts that repeatedly carry growing chunks of ice upwards into the clouds. Unlike freezing rain, graupel or ice pellets (that are softer and smaller in size), hail is hard as stones, bigger in size and causes extreme damage (dents in metal etc)... In general, hail is difficult to predict as there are quite a few ingoing influences and complicating factors that interfere with the course of the storm.

    As @JimInSanDiego correctly summed it up: Hail is a warm weather issue, while freezing rain or ice pellets (sleet) are manifestations of cold weather.


  • administrators

    Here is a quick tutorial to describe the differences between: hail, graupel (soft hail / snow pellets), ice pellets (sleet) and freezing rain. Wikipedia puts it this way:

    HAIL is a form of solid precipitation. It is distinct from ice pellets (American sleet), though the two are often confused. It consists of balls or irregular lumps of ice, each of which is called a hailstone. [...] Unlike other forms of water ice such as graupel, which is made of rime, and ice pellets, which are smaller and translucent, hailstones usually measure between 5 millimetres (0.2 in) and 15 centimetres (6 in) in diameter.
    In more detail: https://en.wikipedia.org/wiki/Hail

    GRAUPEL (from German language), also called SOFT HAIL or SNOW PELLETS, is precipitation that forms when supercooled water droplets are collected and freeze on falling snowflakes, forming 2–5 mm (0.08–0.20 in) balls of rime. Graupel is distinct from hail, small hail and ice pellets: the World Meteorological Organization defines small hail as snow pellets encapsulated by ice, a precipitation halfway between graupel and hail.
    In more detail: https://en.wikipedia.org/wiki/Graupel

    ICE PELLETS (American: SLEET) are rain drops that have frozen before they hit the ground. When they hit the ground, they bounce. Ice pellets are also called sleet and can be accompanied by freezing rain. In winter, precipitation usually begins falling out of a cloud as ice particles.
    In more detail: https://en.wikipedia.org/wiki/Ice_pellets

    FREEZING RAIN is the name given to rain precipitation that freezes on contact on surfaces maintained at temperature below freezing by the ambient air mass. Unlike sleet, a mixture of rain and snow, ice pellets, or hail, freezing rain is made entirely of liquid droplets. The raindrops become supercooled while passing through a sub-freezing layer of air hundreds of meters above the ground, and then freeze upon impact with any surface they encounter...
    In more detail: https://en.wikipedia.org/wiki/Freezing_rain


  • administrators

    Here I found some interesting link with illustrative pictures:
    Will it [freezing] RAIN, SLEET or SNOW?

    http://www.weather.gov/source/zhu/ZHU_Training_Page/winter_stuff/winter_wx/winter_wx.html


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