Virga Fest
Announcement: The Northwest Weather Workshop is on Apr 27-28
The NW Weather Workshop is the primary annual coming together for those interested inward Northwest meteorology. This twelvemonth nosotros volition have got a major session on the meteorology of NW wildfires in addition to others on other aspects of our regional weather. The gathering takes house at the NOAA facility inward Seattle. To sentiment the agenda in addition to to register, larn to the meeting website. The workshop is opened upwards to everyone, but registration is required.
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During the past times few days I have got received nearly a half-dozen emails amongst pictures in addition to videos of beautiful tendrils of atmospheric precipitation falling out of convective clouds, in addition to so this is a practiced fourth dimension to present yous some in addition to utter well-nigh this stunning weather condition feature.
To warm yous up, hither is an amazing example, 1 visible from the Seattle Space Needle Panocam at seven PM Sabbatum evening. A lonely cumulus tower developed over NE Seattle inward the minutes earlier in addition to if yous lookout adult man a fourth dimension lapse yous could consider the atmospheric precipitation autumn out of the cloud. It didn't wound that this was around sunset.
Since I am an academic, let's get down amongst some definitions regarding the phenomenon inward question.
Virga is defined as:
"an observable streak or shaft of atmospheric precipitation falling from a cloud that evaporates or sublimates earlier reaching the ground."
So technically, the atmospheric precipitation (liquid or solid, pelting or snow) should evaporate earlier reaching the surface if it is virga. If it does non evaporate earlier hitting the solid lay down nosotros purpose some other term: precipitation shaft.
But basically, they are the same thing. So inward the pictures above, nosotros have got a mixture of the ii at the same time.
Now it turns out nosotros had a lensman merely to the due west of the same virga/precipitation shaft. Her is a wonderful shot past times Kathy Scott at seven PM from her advantage betoken inward Maple Leaf inward North Seattle. Clearly the atmospheric precipitation shaft is to the eastward of her (you tin john consider the Cascades inward the background).
The radar epitome at the same fourth dimension shows the cumulus cell's precipitation, but is non impressive:
Virga is normally associated amongst evaporative cooling, every bit atmospheric precipitation falls into air that is unsaturated (less than 100% relative humidity) below. If yous are below a cloud that starts to precipitate...and hence producing virga... yous powerfulness good experience a nail of cooler air because the atmospheric precipitation had evaporated earlier it reached the surface where yous are.
And because cool air is denser in addition to hence heavier than warmer air, the evaporating air tends to accelerate downward. And when the downward moving air slams into the surface it splays out, producing enhanced horizontal winds.
Did that hap terminal night? You bet. Let's choice a place due west of Maple Leaf (see map below) from the stations available from the wonderful weatherunderground.com site.
Here are the observations at the place (click on the epitome to expand). If yous await closely inward the commencement panel yous volition consider a abrupt drib inward temperature in addition to a ascent inward dew betoken (a stair out of the total of wet inward the air) around seven PM.
In the 2nd panel in that place is current of air speed....a notable acceleration was observed. The 4th panel should an precipitous modify inward current of air direction from the cool, downdraft air. But in that place was no accumulation of atmospheric precipitation (third panel)...it has evaporated.
Interestingly, I alive closed to the higher upwards station in addition to I experienced some very, really calorie-free showers at that exact time. I know that because I trying to repair my sometime wheelbarrow at that time. And a chill developed inward the air.
Finally, if yous actually desire to experience virga, 1 has to sentiment an animation. So hither is a wonderful instance provided past times Greg Johnson of SkunkBay Weather for a convective trouble that moved through his due north Kitsap place of Wednesday. Enjoy.
Squall Moving Through... From The Air in addition to Ground.... 3/25/18 from SkunkBayWeather on Vimeo.
The NW Weather Workshop is the primary annual coming together for those interested inward Northwest meteorology. This twelvemonth nosotros volition have got a major session on the meteorology of NW wildfires in addition to others on other aspects of our regional weather. The gathering takes house at the NOAA facility inward Seattle. To sentiment the agenda in addition to to register, larn to the meeting website. The workshop is opened upwards to everyone, but registration is required.
_________________________________________________________
During the past times few days I have got received nearly a half-dozen emails amongst pictures in addition to videos of beautiful tendrils of atmospheric precipitation falling out of convective clouds, in addition to so this is a practiced fourth dimension to present yous some in addition to utter well-nigh this stunning weather condition feature.
To warm yous up, hither is an amazing example, 1 visible from the Seattle Space Needle Panocam at seven PM Sabbatum evening. A lonely cumulus tower developed over NE Seattle inward the minutes earlier in addition to if yous lookout adult man a fourth dimension lapse yous could consider the atmospheric precipitation autumn out of the cloud. It didn't wound that this was around sunset.
seven PM Sabbatum March 24
Since I am an academic, let's get down amongst some definitions regarding the phenomenon inward question.
Virga is defined as:
"an observable streak or shaft of atmospheric precipitation falling from a cloud that evaporates or sublimates earlier reaching the ground."
So technically, the atmospheric precipitation (liquid or solid, pelting or snow) should evaporate earlier reaching the surface if it is virga. If it does non evaporate earlier hitting the solid lay down nosotros purpose some other term: precipitation shaft.
But basically, they are the same thing. So inward the pictures above, nosotros have got a mixture of the ii at the same time.
Now it turns out nosotros had a lensman merely to the due west of the same virga/precipitation shaft. Her is a wonderful shot past times Kathy Scott at seven PM from her advantage betoken inward Maple Leaf inward North Seattle. Clearly the atmospheric precipitation shaft is to the eastward of her (you tin john consider the Cascades inward the background).
The radar epitome at the same fourth dimension shows the cumulus cell's precipitation, but is non impressive:
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| NWS radar epitome at 6:59 PM 24 March |
And because cool air is denser in addition to hence heavier than warmer air, the evaporating air tends to accelerate downward. And when the downward moving air slams into the surface it splays out, producing enhanced horizontal winds.
Did that hap terminal night? You bet. Let's choice a place due west of Maple Leaf (see map below) from the stations available from the wonderful weatherunderground.com site.
Here are the observations at the place (click on the epitome to expand). If yous await closely inward the commencement panel yous volition consider a abrupt drib inward temperature in addition to a ascent inward dew betoken (a stair out of the total of wet inward the air) around seven PM.
In the 2nd panel in that place is current of air speed....a notable acceleration was observed. The 4th panel should an precipitous modify inward current of air direction from the cool, downdraft air. But in that place was no accumulation of atmospheric precipitation (third panel)...it has evaporated.
Interestingly, I alive closed to the higher upwards station in addition to I experienced some very, really calorie-free showers at that exact time. I know that because I trying to repair my sometime wheelbarrow at that time. And a chill developed inward the air.
Finally, if yous actually desire to experience virga, 1 has to sentiment an animation. So hither is a wonderful instance provided past times Greg Johnson of SkunkBay Weather for a convective trouble that moved through his due north Kitsap place of Wednesday. Enjoy.
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