Vaisala LM21 - Table 4 Background Luminance Values in Relation to the

Chapter 2 ____________________________________________ Product Overview
VAISALA__________________________________________________________15
Typical background luminance values in relation to the
human eye are presented in Table 4 below.
Table 4 Background Luminance Values in Relation
to the Human Eye
Condition Illumination
Threshold (lux)
Background
Luminance (cd/m
2
)
Night 8 x 10
-7
4 - 50
Intermediate 8 x 10
-5
51 - 999
Normal day 8 x 10
-4
1000 - 12 000
Bright day (sun,
fog)
8 x 10
-3
More than 12 000
LM21 Background Luminance Sensor supplies continuous
background luminance values for RVR calculations.