
It is rainy day under poor weather condition, but M1A1s with thermal sight cannot see infantry target 300m~400m away. The tank failed to recognize enemy MG team shooting at the tank for about a few minutes.

Another HMG team shooting at tanks, and M1A1s cannot recognize enemy HMG team. This is even ~100m distance.

They figured out HMG team about 1 min later and killed them. But this totally don't make sense, M1A1 with thermal sight cannot see enemy HMG team shooting at them for a while, which was 100m in front of them?

Now it is night, but M2A2s with thermal sight coudln't see enemy infantry about 200m~300m in front of them. Friendly infantry, who approached to the right in front of enemy mech infantry recognize them, and shooting at them. Then M2A2s followed.
I saw thermal sight units see enemy vehicle in rainy night much better. But against infantry, I guess thermal sight receives bit too harsh penalty.
1st gen thermal suffered from low resolution, but still it can show some white signal on the screen, even against enemy infantry. I was expecting to see at least yellow unidentified icon, if fails to recognize due to rain. But as you see from above pics, not even yellow icon appears, thermals are blind as same degree as bare eye sight against infantry.
Thermal sight during good day should be able to detect enemy infantry, but when I play AB, vehicles with thermal sight still fails to detect and recognize enemy infantry in broad daylight. I feels like detection ability of thermal sight against enemy infantry is a bit undervalued despite of weather. Vehicles with thermal should approach too close to detect and recognize enemy infantry (from further distance in nice day than rainy day).
AFAIK fog can degrade thermal in moderate degree, depending on how thick the fog is. But in relative sense, rain doesn't hinder thermal that much like the fog. But I feels like rain in this game induces overpenalty to thermal sight.
ps) I think the response of thermal sight in the screenshot I listed in here is more looks like the response under foggy day environment, not rainy day environment. Rain degrades thermal, but not that much. I think, thermal sight units should be able to detect at least unidentified yellow icon after around 30sec observation against enemy infantry under circumstances of screenshot. Those opposite infantry were close.
