hey rahul....all ur concepts are really nice
n u really gud with d choice of colors...
the only thing i felt is missing a bit is color prespctive,
the objects in forground have the same intensity or contrast in comparision to bckgrnd, for example like in d third picture whr one cannot figure out the cloud position and dimension, whtr it is gng in to prespective or its gng straight..
it shld blend a bit, with the environment...
But its all my point of view, i could be wrong.
all the best...!!