How does friction affect the angle of surface wind relative to the isobars?

• A. It remains parallel
• B. It angles toward low pressure
• C. It angles away from low pressure
• D. It has no effect

Answer: (B)

The correct understanding is that friction causes the surface wind to angle toward low pressure rather than remaining parallel to the isobars as it would in the absence of friction.

When wind flows in the atmosphere, particularly at higher altitudes where friction is minimal, the wind generally moves parallel to isobars due to the balance between pressure gradient force and Coriolis force. However, at the surface, friction from terrain, vegetation, and other obstacles disrupts this balance. As air moves from high to low pressure, the frictional forces exerted by the surface slow down the wind and cause it to veer, making it cross the isobars.

This veering results in the wind approaching the low-pressure area more directly, leading to an angle toward low pressure. Therefore, the surface wind no longer runs parallel to the isobars but instead is drawn into low-pressure areas due to the effect of friction. Understanding this behavior is crucial for interpreting weather patterns and predicting local wind conditions effectively.