Dogs barking at odd hours

Dogs have this weird sense of smell that they start barking at if they feel that something is wrong.

Well that fascinated me when I was continuously noticing that the dogs in my vicinity would start barking at odd hours in the middle of the night. A very much observed time was at 2:00am in the morning. Reading this might have raised a lot of eyebrows in fascination. I still wonder why they do it. Meaning they are still continuing to bark at odd hours in the middle of the night. And now, they have also started crying loudly. My dad has to put water on them to shoo them away, as many of us believe that dogs crying isn’t a good sign.

So, my question here is that: Why do dogs start barking at such odd hours?
Are they calling out the fellow dogs?
Or is it something else?
Have you ever noticed such a behaviour in your dogs if you have one?
Looking forward to responses.

Thanking CUP for giving us this opportunity to showcase our observations and discuss about it with others!