Chronograph in cloudy and / or relatively dark weather - possible or not !?

Hi

Have no issues with my Caldwell Chrony and light kit. Read and follow instructions easy and I think accurate enough. 
Love the free app connection ios , cannot comment on Android, but assume that good too.
The ir light kit connected to main allows shooting indoors and repeatable conditions everytime. 
Very very few errors, tripod supplied with bubble level ensures accuracy.
Downside a Pcp indoors surprisingly loud. 

Have a old shooting chrony, over 20 years, occasionally use both outside in right conditions, very similar readings. 

I am not a trader or related in anyway , just my own opinions.

safe shooting

Hummm.......I've never tried shots at different heights above the chrony. Instead of guessing I wrapped some yellow tape around a "light stand" at two levels, the lower level at 5" above the sensors is my normal height with muzzle placement 1 foot away. I shot 5 pellets at my normal muzzle placement and 5 shot about 3" higher........Here's a pic of the chrony setup with chrony lights on...............

Here are the readings at low tape............
860 865 860 862 864

Here are the readings at the high tape........
862 860 859 859 860

IMHO....there was no difference taking readings at 5" above sensors or 8" above sensors using my Prochrono with Prochrono light kit.

Now some general "chrony reading comments"........
1. Velocity variations can be caused by the pellets themselves.
2. The "health" of gun itself can cause velocity variation readings.
3. Dieseling between the shots will affect the readings (related to #3).
4. Variations in the angle of the shots over the sensors will affect readings.
5. Even environmental conditions can affect the readout.........so on and so forth!!

For my testing I used............
A. .177 HW95 with home turned oring sealed piston cap and fitted with a "home rolled" spring kit based on a light wire Maccari E3650 spring (35 coils of .120 wire with .515 nom ID) lubed with non-dieseling Dupont Krytox GPL205.
B. The pellets were die "B" Crosman Premiers from the 1250 count boxes. They were head sized to 4.50mm using a home made pellet sizer and they were sorted by weight. The pellets in the test weighed between 8.00 and 8.06 grains.

Personally........I'm not looking for a precise measurements. As long as my velocity spread doesn't exceed much more than 10fps a I consider "all is well" .
Then again, as a general break barrel shooter and not a shooter usin' a fine German UberHyperSpitzen PCP, perhaps my findings aren't relevant to some!