Which of the following affects visibility the most in an urban area?

Haze is the factor that most significantly affects visibility in urban areas. It refers to the presence of fine particulate matter and pollutants in the air, such as dust, smoke, and industrial emissions. These particles scatter and absorb light, reducing the overall visibility. In urban environments, where there are higher levels of pollution due to traffic, industrial activity, and construction, haze can be particularly pronounced. This scattering effect can be exacerbated by weather conditions, which can cause pollution to accumulate, further diminishing visibility.

High humidity, while it can have an impact on visibility by creating conditions for fog, generally does not have as profound an effect as haze in urban centers. Atmospheric pressure changes typically do not directly influence visibility; instead, they can be associated with changes in weather patterns that may indirectly affect visibility. Temperature fluctuations can influence factors like the formation of fog or the stability of air layers, but they are less immediately impactful on visibility in comparison to haze.