The correct answer is B) stratiform clouds. Warm air masses generally have stratiform clouds, which are broad, flat cloud layers that produce steady, light precipitation. This is because warm air masses are characterized by stable atmospheric conditions, with air slowly rising and cooling. The slow, steady cooling of the air leads to the formation of stratiform clouds rather than the more turbulent, convective clouds associated with heavy precipitation. The other options are incorrect because: A) heavy precipitation is more typical of unstable air masses, C) turbulence is more common in cold air masses, and D) good visibility is not a defining characteristic of warm air masses.