Looking for a semi scientific explanation of the conditions that are the most conducive to having a visible vapor trail (or bullet trace as some call it.)
Range Report Optimal conditions for vapor trail?
- Thread starter Doyputasos
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Don't know the optimal scientific answer, but high humidity and 500+ yards made for a fun morning.
I don't have your scientific answer, but I have a simple cell phone picture that captured the vapor trail of my 9mm at an indoor range. I was not expecting it, but it makes a good conversation starter.
Humidity will cause a bullet to leave a "contrail" much like an aircraft engine. However, under the right lighting conditions, it is possible to see the pressure differential left in the air by a passing bullet due to the compression and expansion of the adjacent air by the shock wave. This pressure difference affects the refractive index of the air around the bullets path and bend light as it passes thru these areas so you see a disturbed "trace" along the bullet's path. This is known as the "schlieren" effect.
Thanks for the posts all. I was not aware that vapor trail and bullet trace were completely different phenomena.
I'm not sure I explained the original question perfectly. I'm looking specifically for the weather conditions that impact (the more common) bullet trace. It seems like the common answer is heat+humidity=trace, but are these two the only high impact factors? What about altitude, light, wind, etc?
I'm not sure I explained the original question perfectly. I'm looking specifically for the weather conditions that impact (the more common) bullet trace. It seems like the common answer is heat+humidity=trace, but are these two the only high impact factors? What about altitude, light, wind, etc?
I'm not positive because I haven't paid attention to this specifically, but it seems like if the mirage is strong, the trace tends to be more visible. Anyone else notice that or am I making things up?
The conditions I've noticed producing the best trace are high humidity, low wind, morning or late afternoon sun. Winds above 10 mph seem to disapate the trace and move it from it's true path. When the sun is directly over head it " washes out" definition of the trace and causes glare. A good spotting scope really helps! Under certain conditions I've seen the glent off the bullet as it travels to the target, much like seeing a 22 lr bullet in the scope as you shoot.
