well... thats a difficult question... theoretically the smoke should rise... But in fact it depends of many things... usually when the weather is good the smoke rises, and when the weather is changing (before rain, as example) the smoke goes randomly, it floats somewhat horizontally... there is a word in english which describes it, but i just cant remember it...
And the smell is still more unpredictable... i think the only law which holds for every possible occasion is the Murphy Law, which states:

"The smell of the weed will go, in the shortest and fastest way, directly to the nostrils of the person which you really DONT want to smell it."

So, be warned...