Which of the following is included in present weather observations?

Present weather observations focus on the current atmospheric conditions that can significantly impact visibility and basic weather conditions at a specific location. Obscuration refers to phenomena that reduce visibility, such as fog, rain, snow, or dust storms. This category is essential because it gives vital information about how weather conditions might be affecting visibility and safety, which is particularly critical for aviation and transportation.

Other options, while related to weather, do not fit the specific criteria for present weather observations. Tornado occurrences, for instance, are reports of significant severe weather events but are not categorized under everyday weather observations. Wind shear is a change in wind speed or direction with altitude, which is crucial for flight safety but is not typically defined as present weather. Air temperature, although relevant to overall weather conditions, is generally considered a data point rather than an immediate weather phenomenon affecting visibility. Thus, obscuration is the most fitting option for inclusion in present weather observations.