Rain over most midwest major city right now!, page 1

There isn't rain over hardly any major city. The only thing I can see that would look like rain are radar rings around major cities where there are radars. What you're seeing when these rings are present is called "Clean Air" mode on the radars.

Clear Air Mode
In this mode, the radar is in its most sensitive operation. This mode has the slowest antenna rotation rate which permits the radar to sample a given volume of the atmosphere longer. This increased sampling increases the radar's sensitivity and ability to detect smaller objects in the atmosphere than in precipitation mode. A lot of what you will see in clear air mode will be airborne dust and particulate matter. Also, snow does not reflect energy sent from the radar very well. Therefore, clear air mode will occasionally be used for the detection of light snow.

The radar continuously scans the atmosphere by completing volume coverage patterns (VCP). A VCP consists of the radar making several 360° scans of the atmosphere, sampling a set of increasing elevation angles. There are two clear mode VCPs.

In clear air mode, the radar begins a volume scan at the 0.5° elevation angle (i.e., the radar antenna is angled 0.5° above the ground). Once it makes two full sweeps (a surveillance/reflectivity sweep and a Doppler/velocity sweep) at the 0.5° elevation angle, it increases to 1.5° and makes two more 360° rotations. For one of the clear air mode VCPs, two full sweeps are also made at 2.5°. Otherwise, at the higher elevations (2.5°, 3.5°, and 4.5°) a single sweep is made (reflectivity and velocity data are collected together).

This process is repeated at 2.5°, 3.5°, and 4.5°. Then the radar returns to the 0.5° elevation angle to begin the next volume scan which will repeat the same sequence of elevation angles. In clear air mode, the complete scan of the atmosphere takes about 10 minutes at 5 different elevation angles.

-Source

These usually indicate little to no rain actually.

reply posted on 23-7-2011 @ 03:10 AM by Misoir

Source

Echoes from objects like buildings and hills appear in almost all radar reflectivity images. This "ground clutter" generally appears within a radius of 25 miles of the radar as a roughly circular region with a random pattern. An mathematical algorithm can be applied to the radar data to remove echoes where the echo intensity changes rapidly in an unrealistic fashion. These "No Clutter" images are available on the web site. Use these images with caution; ground clutter removal techniques can remove some real echoes, too.

Under highly stable atmospheric conditions (typically on calm, clear nights), the radar beam can be refracted almost directly into the ground at some distance from the radar, resulting in an area of intense-looking echoes. This "anomalous propagation " phenomenon (commonly known as AP) is much less common than ground clutter. Certain sites situated at low elevations on coastlines regularly detect "sea return", a phenomenon similar to ground clutter except that the echoes come from ocean waves.

Radar returns from birds, insects, and aircraft are also rather common. Echoes from migrating birds regularly appear during nighttime hours between late February and late May, and again from August through early November. Return from insects is sometimes apparent during July and August. The apparent intensity and areal coverage of these features is partly dependent on radio propagation conditions, but they usually appear within 30 miles of the radar and produce reflectivities of <30 dBZ.

It is not rainfall as almost every city (excluding areas with obvious rainfall) are well below 30 dBZ which means that it is not necessarily any sort of precipitation being picked up rather it can be bugs, insects, ground clutter, etc...

reply posted on 23-7-2011 @ 03:10 AM by saucerboy

i live in minneapolis and according to this map it would be raining, but according to my eyes it is not, my guess is that it is just low clouds it was pretty hazy not to long ago

reply posted on 23-7-2011 @ 03:12 AM by jazkaat

reply to post by BriGuyTM90

what you see is the Doppler radar picking up particulates in the air. it could be water/ice/snow particles, but is probably dirt/dust/smoke etc.

reply posted on 23-7-2011 @ 03:37 AM by DarkSarcasm

Originally posted by porschedrifter
Not going to lie, look at how odd this is... Loop the feed.

Very odd spots of radar action going on here: radar.weather.gov...

edit on 23-7-2011 by porschedrifter because: (no reason given)

Well, I've never seen this map on weather.com before. Very interesting. It could be dust/dirt but it is more likely.to be air with high humidity levels or even possibly particulate matter from industrial exhaust. Pollution can show up as well. Pollution would be my guess as when you look at that radar the readings only go so far out from the cities but do not extend all the way to the edge. This could also be caused by the fact that the further out the radar signal is on the available scan area the less time the radar will pick up readings, meaning, the radar just doesn't have enough time to notice/locate the particles.

reply posted on 23-7-2011 @ 04:27 AM by LazloFarnsworth

Detroit, Chicago, Toledo, Cleveland, Cincinati tonight...clear skies after bright near 100 degree days. Great clear days all day today and night... all night here. Lots of stars....

Pages: ^^TOP^^