Nvg Met Flashcards
Which astronomical factors have an effect on the night illumination?
Sun elevation
Moon elevation
Moon phase
Other sources of natural light
Which meteorological factors have an effect on the night illumination?
Clouds
Percepitation
Ground conditions
Define the term “Civil twillight”
The time after SS and before SR when the sun is up to 6 deg below the horizon
Define nautical twillight
When the sun is 6 up to 12 deg below the horizon.
Dark night condition after sunset?
When the sun is more than 16 deg below the horizon
Explain moon brightness
Brightness of the horizontal ground caused by the moonlight, NOT the brightness of the moon itself.
Given in % of the full-moon-light at the average moon-earth distance in case of full zenith.
Explain meteorological optical range, MOR
The horizontal distance on which an attenuation of white light by 95% takes place.
Write down the limiting value for the nvg range for flights with night vision goggles.
1,5km nvd range
0,5 mlx
Explain chlorophyll effect
High degree of reflectivity in near IR WAVELENGTH, ex grass and leaves.
Good quality of NVG image in seasons when bushes and trees have leaves