The amount of smoke generated is a function of the way the locomotive is being fired and the capacity of the boiler to generate sufficient steam to do the job the locomotive is being asked to do. British steam locomotives sacrificed easy maintainability for greater efficiency, therefore used less coal than their North American counterparts, but spent more time in the engine sheds. A properly fired steam engine should only show a slight haze coming from the stack.
Most tourist railways purposely overfire their steam locomotives because the tourists expect to see black smoke. If you see "white smoke", that isn't actually smoke, but exhaust steam, which is a lot more visible in cold weather.
Most tourist railways purposely overfire their steam locomotives because the tourists expect to see black smoke. If you see "white smoke", that isn't actually smoke, but exhaust steam, which is a lot more visible in cold weather.