"120,000 lux Brightest sunlight
110,000 lux Bright sunlight
20,000 lux Shade illuminated by entire clear blue sky, midday
10,000 -25,000 lux Typical overcast day, midday
<200 lux Extreme of darkest storm clouds, midday
400 lux Sunrise or sunset on a clear day (ambient illumination).
40 lux Fully overcast, sunset/sunrise
<1 lux Extreme of darkest storm clouds, sunset/rise, moonlight"
Courtesy of Wikipedia...
"The sun averages 7k lumens,most plants have adapted to be able to handle the sun. Over 10k or about 110,000lux if your a weirdo will bleach your plants. That's the sun at its strongest...when this bleaching occurs the plant is not being able to keep up chlorophyll production at rates necessary...likewise 2100 lumens is required to sustain photosynthesis
Heat burns the plant in a different way, similar to having too much wind. From moisture being drawn out the leaves (transpiring)faster than the plant can replenish"
Courtesy of me...Googling myself again
Oh and lights are rated at 1 foot