There is definition to them. Maybe your screen has a more faulty calibration than normal. It's not impossible.
Try out my weather mod otherwise. It includes a weather called evening storm, will give you more definition for sure. Dont forget to apply the pp-filter along with it since it's made for that.
http://www.racedepartment.com/threads/tt-alternative-weather-weathers-ppfilter.112220/
But first I would go into your screens menu (I have no idea what kind of screen you use) and turn off all extra on top stuff like added contrast boost, blackness and so on. Many times they give you contrast in one part of the spectrum and you completely lose it in another (spectrum between black and white).
Anyway. The difference between different screens is much bigger than people think. It can vary very much. For example, it come out an article some years ago that researchers concluded that humans percieve the blue spectrum brighter than the varm/red even at the same luminosity. This made screen developers think if our screens look brighter (hence more contrasty) we will stand out in the shop next to the competition. So they calibrated their monitors towards blue, way off neutral calibration. Most consumer monitors and tv's today are calibrated off neutral towards blue. Which basically makes comparing one image file on the internet between to pc's impossible. One person simply have no idea what the other one see's.