During a nocturnal inversion, what happens to wind below the inversion zone?

During a nocturnal inversion, what happens to wind below the inversion zone?

• A. Wind increases at the surface.
• B. Wind becomes gusty at low levels.
• C. Wind reverses direction below the inversion.
• D. Wind becomes calm below the inversion zone.

Answer: (D)

Nocturnal inversions create a very stable lower atmosphere that suppresses vertical mixing. As the ground cools at night, the air near the surface becomes cooler than the air above, forming a layer that resists mixing with the air above. With little turbulence and frictional production of mixing energy at the surface, the wind slows and can become calm. So, below the inversion zone, the wind tends to be calm, while winds above the inversion can remain stronger and wind shear may occur at the top of the inversion.

Nocturnal inversions create a very stable lower atmosphere that suppresses vertical mixing. As the ground cools at night, the air near the surface becomes cooler than the air above, forming a layer that resists mixing with the air above. With little turbulence and frictional production of mixing energy at the surface, the wind slows and can become calm. So, below the inversion zone, the wind tends to be calm, while winds above the inversion can remain stronger and wind shear may occur at the top of the inversion.