June 9th 04, 04:15 PM
|
|
|
On 8 Jun 2004 19:50:30 -0700, (Matthew
Spaltro) wrote:
I am hearing Southwest Harbor Maine coast guard group in South
Portland maine. A 150 mile distance. It's not skip is it? Is it the
weather pattens we have been getting here in Maine? Yesterday was in
the 50-60s and today is in the 70s.
Probably the result of temperature inversion ducting.
Where I live (Tonawanda, NY - along the Niagara River between Buffalo
and Niagara Falls) we get ducting all summer long here due to our
proximity to Lake Erie and Lake Ontario. It's not unheard of for hams
in Cleveland to get into the Buffalo repeaters with 5-watt handhelds.
We also hear Coastguard Canada from up in Sarnia (across from
Michigan) on marine Ch. 16 down here quite a bit, low band fire calls
on 46 megs from Watertown and the Finger Lakes region, Rochester Fire
booming in loud and clear in Buffalo 75 miles or so away, etc.
What usually happens here in Western NY is that when it's hot out
during the summer, the air is so much warmer than the water in the
lakes that once it gets dark out, a layer of cooler air forms along
the lake front and starts moving inland. In addition to patchy ground
fog (grin), this also produces a temperature inversion that can duct
VHF signals for hundreds of miles. The effect is more pronounced at
40-50 MHz than it is at 160 MHz, but with Lake Ontario it has even
ducted signals on 440 MHz for 75-100 miles.
Lately, I've noticed that at times in the local spring, we've had a
few instances where the inversion occurs because the water is warmer
than the air and a layer of warmer air forms and moves inland. With
your proximity to the ocean - which is a hell of a lot bigger than any
lake - I'm not at all surprised that you would observe this phenomenon
up there a well.
Enjoy the chance to log some stuff you wouldn't normally find within
range of your receivers. If you run CTCSS on your scanners, you might
want to disable it and see what you can pull in on other frequencies,
you might find some other surprises in store for you, too.
73 DE John D. Kasupski
Tonawanda, New York, USA
Amateur Radio (KC2HMZ), HF/VHF/UHF Monitoring (KNY2VS)
Member ARATS, ARES, RACES, WUN
|