Does fog effect radar?

**holein1** · 11-20-2005, 12:15 PM

Lately around where I live the fog has been getting quite thick (the kind where you can only see about 75 to 100ft in front of you)! When I turn out onto my main street there is about a mile long straight stretch and at the end of that there is a little cut out area on the side of the road where a certain sheriff's deputy likes to hide! Now when the sky's are clear and he's running his k band radar I pick him up as soon as I turn onto the main road aprox. one mile cause the dummy leave's his unit on, however the last few day's and night's when it was nice and foggy my detector didn't pick the sheriff's radar up until about the half way mark 1/2 mile! I didn't think the fog would have this much of an affect on radar, has anyone else ever experienced this?

**TeamQuack** · 11-20-2005, 12:57 PM

yeah ive read before that fog does effect radar. but dont call the leo a dummy cause you wouldnt want him to be smart :twisted:

i know rain effects radar so fog might as well, just water in a different form.

**tjbender** · 11-20-2005, 01:10 PM

The easiest effect I can think of would be that the fog cuts the LEO's visibility way down, and they can't see your car to aim at it past a quarter-mile or so, even on a straight road.

**holein1** · 11-20-2005, 01:15 PM

Originally Posted by bcorby

The easiest effect I can think of would be that the fog cuts the LEO's visibility way down, and they can't see your car to aim at it past a quarter-mile or so, even on a straight road.

The sheriff's dept. has the radar unit's mounted on the inside pillars of their car's and sit in the same spot parallel to the road I'm driving on.

**Carlos from Spain** · 11-20-2005, 01:24 PM

Humidity in the air decreases the propagation of the radar microwaves, so the signal reaching the detector is weaker under foggy conditions.

**GTO_04** · 11-21-2005, 07:45 PM

Fog, rain or snow will probably have even more of an effect on the police radar, because it must deal with a reflected signal. It must travel to the vehicle be reflected, and travel back.

Cops don't normally run radar much in heavy rain or fog. Or at least they don't like to pull people over in those conditions.

GTO_04

**RadarHell** · 11-21-2005, 08:11 PM

Originally Posted by Carlos from Spain

Humidity in the air decreases the propagation of the radar microwaves, so the signal reaching the detector is weaker under foggy conditions.

K band (24GHz) Radar runs near the frequency of water vapor, around 22GHz. This causes the reduction an officer has in pickup but does not affect the accuracy of the radar itself. In turn this would cause you unit not to pickup an earlier signal too since the water vapor absorbs the output signal and return.

If you also notice, you are able to receive an earlier signal on a cold night with not atmospheric moisture/clouds. In cooler/colder weather there is less moisture for the air unlike warm/hot weather.

**LS2** · 11-21-2005, 10:56 PM

Originally Posted by holein1

Originally Posted by bcorby

The easiest effect I can think of would be that the fog cuts the LEO's visibility way down, and they can't see your car to aim at it past a quarter-mile or so, even on a straight road.

The sheriff's dept. has the radar unit's mounted on the inside pillars of their car's and sit in the same spot parallel to the road I'm driving on.

Which detector are you using?

**stalker** · 11-21-2005, 11:10 PM

you will find he has the transmitting power turned down, in fog or rain the radar operators cant get a reading as far away as if it was clear weather.

Ik know for a fact in bad weather operators dont use max power and that is why you picked him up a lot later than normal.

**jimbonzzz** · 11-21-2005, 11:17 PM

I don't know of any radar units that have variable power. Most have a "sensitivity" or "range" control, but that does not change the output power at all.

Jim