What the Lux?

[Ali Barber]

I'm looking for some help. Does anyone know how the forecasters work out what the lux levels are for NVG operations? Similar question for thermal cross-over.

If you're worried about security, E-mail me with your contact number and I'll explain who I am and what my interest is.

Thanks in advance.

[Tiger_mate]

A quick internet search has determined that a degree in mathematics and information gleened from a US defence met satellite is used. On top of this terrain and cloud cover information is put into the pot, but urban lighting is not specifically included as each area has a default setting that should account for this. I tried to cut and paste the relevent bits but my PC froze every time. Perhaps the US Defence Department want you to find out for yourself.

Google web search using keywords: night - vision - lux - met

[flygunz]

You probably know that the determination of lux levels for nvg operations is a well established and accurate process. All met officers providing forecasts for the military forecast the nightly levels on request. How they do it is smokescreens and mirrors as I never asked but if you talk to any met person I'm sure the explanation is easily understood.
Thermal crossover is a different case, the accurate determination of crossover hasn't been nailed yet. We can all say it will happen twice in a period, theoretically what surfaces will intermingle and what surfaces wont. As an operator I got to the point where I could recognise it early enough not to get suprised when it went all gloopy, but the characteristics change depending which country you're trying to oogle at!
There is a basic computer programme about thats supposed to get close but I wouldn't trust it without data.