Which of the following factors is not included in present weather?

Present weather reports include observable phenomena that affect visibility and flight safety, typically focusing on conditions that can be seen or measured at a given time. Precipitation, obscurations, and phenomena like sandstorms are all elements that can impact weather conditions directly through their measurable effects on visibility and the atmosphere.

Cumulonimbus clouds, while significant in terms of weather hazards such as thunderstorms, severe turbulence, and potential for precipitation, do not qualify as a present weather factor because they represent a type of cloud rather than a weather phenomenon that is observable at the surface level. Present weather is more concerned with conditions like rain, fog, and dust storms that can directly influence operational decision-making for pilots. This distinction helps in maintaining clarity in weather reporting and enhances situational awareness for those in aviation.