Pretty grainy. Did you use a tripod since you at home? Blue sky don't look natural at all. What's so interesting about the cloud anyway? It doesn't seem to form a pattern. It look so messy to me... Sorry if i sound so harsh..
There were some very dark patches of deep blue on the cloud, which I found interesting as I had never seen it before. The deep "unnatural" colours are the result of post-processing. I'm a fan of greater saturation, just my personal preference. There's no point using a tripod in broad daylight unless your arms are made of jelly, this again is in my personal opinion. I shot the image at ISO 250, and personally I think it's fairly clean. The "graininess" is likely as a result of compression.
looks fine to me, not grainy either just somewhat out of focus. the bluecast does seem unnatural but its your choice as an artist i do have beef with the composition though -- plane closer to edge of frame would be better (idea of exit)
i recognize that place i think, it...reminds me of this thing near pasir panjang! i like this shot. i have seen those clouds as well, they aren't exactly unusual but a sight to behold nonetheless! ^^ and i agree with your thing about tripods! i don't carry my tripod unless i am planning to do small apertures!
I noticed as well that it was a tad out of focus. Pretty odd since I used it at infinity. The crane was about 100-200m away and I used a 200mm lens. I reprocessed the image to lighten the blue cast. Better?