I've been playing around with my fancy new jap/thai watch and watching the effects of weather on shooting. To cut the story short - the air pressure went up 4 hpa and the air temp fell 5deg, and the measured altitude fell 20m.
The results - my springer putting out 10.5ft/lbs on a normal humid med pressure day lost a fair bit of power. The POI fell a good inch and a half
The interesting thing is that normally bad weather is associated with lower measured pressure but the air is far denser. That means more air particles in your piston chamber - faster muzzle velocity. Funny how the cold weather came with a high this time. The fall in POI means that sparce air (HP) doesnt decrease drag enough to compensate for the loss in power. Humidity does bugger all IMO.
I wouldn't expect a pcp shooter to notice much of a drop at all. Maybe even hit a bit high
Last Edit: Apr 29, 2013 19:00:37 GMT 11 by timfoye