This afternoon and I am sure every afternoon for the next 4-6 months the tempreture and the humidity of the days will increase. These days are very common during the summer months in the northern parts of Australia. So with each afternoon the storm clouds build up at around 4.00 and we get formations unlike this one or better each day. As I was taking this photo there are very dark rain clouds behind me and I hope that this afternoon we get some much needed rain as its only rained here twice since mid April, and as you can see in the foreground its very dry.
Tony Middleton has been kind enough to give me a full explanation of the type of storm cloud it is, Please read his comments below. Thanks again Tony.