The sun in Carnoustie

I went to Carnoustie today, what a lovely place. I managed to fit a five minutes walk on the beach while waiting for my train home. I really did wish I had longer; the sun was shining even though it was bitterly cold.

I tried many shots at the sun over the sea, however, none of them turned out how I remember it! The sun was a perfect rounds shape; here its more of a blob!

Please help me? is this because of the lens I?m using , the lack of filters or something else like my lack of experience?