Defining rainfall: light, moderate, heavy

[HamishMcBush]

From Wikipedia:

Rainfall intensity is classified according to the rate of precipitation:

• Light rain — when the precipitation rate is < 2.5 mm (0.098 in) per hour
• Moderate rain — when the precipitation rate is between 2.5 mm (0.098 in) - 7.6 mm (0.30 in) or 10 mm (0.39 in) per hour
• Heavy rain — when the precipitation rate is > 7.6 mm (0.30 in) per hour, or between 10 mm (0.39 in) and 50 mm (2.0 in) per hour
• Violent rain — when the precipitation rate is > 50 mm (2.0 in) per hour

Nothing about visibility - could depend on how "clean" the rainwater is; possibly you can still see for over 1km in violent rain consisting of clear droplets, but dirty light rain could alter the visibility more dramatically.

However you could try here:
https://www.google.co.uk/url?sa=t&rc...25596728,d.ZGg