Originally Posted by Werkin

Here's what DiNotte Lighting USA had to say about this and a related lumen question:
...it takes a really bright white light to be visible during the day time...lumen output is a reference when talking about the same color -and when talking about using it to see the amber lights put out less lumens than white (or red), but in traffic an amber light is an appropriate light for a front light, and the lesser lumen amber light is more visible than a similar lumen white light.

DiNotte's "best" amber recommendation for daylight only, model 800A - http://store.dinottelighting.com/amb...ight-p126.aspx
Their day + night recommendation, 1200L or XML-3.