what weather conditions affect reception? like cloud covers,no clouds, winter&summer months, night, day can anyone explain when is the best times to listen for DX and Skip
thanks
thanks
Weather Affecting Dx And Skip
- Thread starter Dispatrick
- Start date
- Status
ka3jjz
Wiki Admin Emeritus
No need to post the same message twice, PGMan - we'll get to it in time...(gentle hint)
Anyway, bookmark this site - this will let you know for a couple of days in advance when it is possible that tropo (the most common form of skip in the VHF/UHF bands) might occur. At the bottom of the page is a link to an intro to the various modes of tropo and what causes them - interesting reading.
http://www.dxinfocentre.com/tropo.html
Do not let the fact that the site discusses this in context of TV/FM skip - the mechanics of VHF/UHF skip are the same regardless of service. 73s Mike
Anyway, bookmark this site - this will let you know for a couple of days in advance when it is possible that tropo (the most common form of skip in the VHF/UHF bands) might occur. At the bottom of the page is a link to an intro to the various modes of tropo and what causes them - interesting reading.
http://www.dxinfocentre.com/tropo.html
Do not let the fact that the site discusses this in context of TV/FM skip - the mechanics of VHF/UHF skip are the same regardless of service. 73s Mike
k9rzz
Member
PGMAN89 said:what weather conditions affect reception? like cloud covers,no clouds, winter&summer months, night, day can anyone explain when is the best times to listen for DX and Skip
thanks
That greatly depends upon what frequency you're interested in.
Under 30 mhz - weather does not affect reception. Rain/snow might affect your antenna system, but it won't generate an opening.
Above 30 mhz - yes, weather can affect your reception.
Try a Google search on "VHF propagation" or similar.
John K9RZZ
I have no clue how I posted it twice idk how to delete it
Hi PG and all,
"what weather conditions affect reception?"
The only weather condition that affects "skip" is a temperature inversion. A warm layer above colder air at ground level forms a duct between two boundary layers, the earth-air boundary and the warm-cool boundary. Being in the troposphere it's called tropospheric ducting or simply tropo. This affects frequencies mostly above 30MHz including microwave which can cause radar ghost returns from objects over the horizon. 100-300MHz seems to be the center of attraction which is why it most commonly occurs on VHF Hi Band but sometimes it gets strange affecting UHF and not VHF. Overall it's rather unpredictable frequency wise.
Sporadic E propagation is caused by clouds of ionized gas forming in the E layer (the second higher, above the D layer) of the ionosphere. These clouds are formed by intense ultraviolet solar radiation which is why it's more common in the summer months when the sun is more or less directly overhead depending on latitude. Southerners love this phenomenon for that reason. Such propagation is most common between 28 and 60MHz but can go as high as 150 or so. Being these clouds drift like any other they can be tracked by noting where signals come from at any given time but the opening must be intense and long lasting, sometimes for several hiours. Most often propagation fails as quickly as it starts which makes it sporadic E in the first place.
F layer propagation occurs mostly in the HF region but during a sunspot maximum can extend into the lower VHF region up to about 60MHz. This is rather rare since the maximum usable frequency (MUF) rarely rises above 30MHz, it takes some intense ionization to push it that far but I have a 6M QSL card from the southern tip of Argentina proving it does. Since F propagation depends on charged solar particles the MUF rarely rises above 15MHz at solar minima such as we're experiencing now. It'll be another 5 years or so before sunspots make the face of Old Sol look like a McDonald's employee again and you'll be in Radio Heaven while Bender is doing time in Robot Hell. (;->)
"what weather conditions affect reception?"
The only weather condition that affects "skip" is a temperature inversion. A warm layer above colder air at ground level forms a duct between two boundary layers, the earth-air boundary and the warm-cool boundary. Being in the troposphere it's called tropospheric ducting or simply tropo. This affects frequencies mostly above 30MHz including microwave which can cause radar ghost returns from objects over the horizon. 100-300MHz seems to be the center of attraction which is why it most commonly occurs on VHF Hi Band but sometimes it gets strange affecting UHF and not VHF. Overall it's rather unpredictable frequency wise.
Sporadic E propagation is caused by clouds of ionized gas forming in the E layer (the second higher, above the D layer) of the ionosphere. These clouds are formed by intense ultraviolet solar radiation which is why it's more common in the summer months when the sun is more or less directly overhead depending on latitude. Southerners love this phenomenon for that reason. Such propagation is most common between 28 and 60MHz but can go as high as 150 or so. Being these clouds drift like any other they can be tracked by noting where signals come from at any given time but the opening must be intense and long lasting, sometimes for several hiours. Most often propagation fails as quickly as it starts which makes it sporadic E in the first place.
F layer propagation occurs mostly in the HF region but during a sunspot maximum can extend into the lower VHF region up to about 60MHz. This is rather rare since the maximum usable frequency (MUF) rarely rises above 30MHz, it takes some intense ionization to push it that far but I have a 6M QSL card from the southern tip of Argentina proving it does. Since F propagation depends on charged solar particles the MUF rarely rises above 15MHz at solar minima such as we're experiencing now. It'll be another 5 years or so before sunspots make the face of Old Sol look like a McDonald's employee again and you'll be in Radio Heaven while Bender is doing time in Robot Hell. (;->)
- Status
Similar threads
