What kind of gnat is this....

Whenever someone posts a request for identification it is customary (first) to give your location in the world. We have a worldwide audience here !

Secondly, the use of derogatory terms is completely unnecessary despite whatever aggravation you are experiencing.

This is a quite small species of fly which I am unfamiliar with. There are a "lot" of small families of flies which only a fly enthusiast would be familiar with or a true Dipterist.

Since you say these are in numbers then I presume they are breeding in some manner in your location. So, it is best to figure out the source of where they are breeding and then treat that location with something to kill off the colony. Then clean the affected area to prevent their return.