`` i have been flying courier duty since i was twelve years old ; i can damned well smell a storm , '' rankin said flatly as caesar came up with them , and twenty minutes later temeraire was forced to concede , as the wind coming towards them began to die away in odd fits and starts , a suggestion of heaviness in the air , and as they flew on , the cloudbank behind grew long and turned a dark , essential blue striped a little with luminous grey and seaweed-greenish bands of color .