indeed some post process is necessary, even with A700, e.g. a few of my sunset shots are all post process by PS for curve or bring out the contrast, or using High Dynamic Range program on the 2nd shots.
I agree with all of their comments. You have something in this picture in your favour - the colour and texture of the cloud. Like what they say, your picture lacks subject. When this is the case, you need VERY strong colours and texture to make your picture interesting. This is evident in ZCF's picture.
Your cropping is quite all right, if you shot this in RAW, you can re-process it using HDR to try and get more saturation and contrast. Try cropping out the land so that your focus is clear - on the clouds' colour and texture. Hope that was useful.