Which of the following factors is NOT typically associated with flow velocity?

Flow velocity in a river or stream is influenced by several key factors, including the geometry of the channel, the quantity of water, and the characteristics of the channel surface. When considering the role of these aspects, channel size and shape determine how much water can flow and how quickly it moves. A wider and deeper channel allows for greater flow velocity, while narrow or shallow channels may restrict it. Similarly, the amount of water flowing—known as discharge—directly affects velocity; more water typically leads to higher velocity.

Channel roughness also plays a crucial role, as it affects the friction between the water and the bed of the river or stream. A smoother channel reduces friction, allowing for higher velocities, whereas a rougher channel increases resistance and slows the flow.

In contrast, air temperature does not have a direct impact on flow velocity. While temperature can influence the density and viscosity of water, affecting overall fluid dynamics, it is not a primary factor in determining the speed of flow in a waterway. Therefore, the correct choice is associated with air temperature, as it is not typically linked to flow velocity in the same way the other factors are.