Characteristics of Marine Inversion/Summer Stratus

 

1.  Onshore pressure gradient induces flow across California current and area of upwelling;

 

2.  Conductional cooling occurs in lowest 100 meters or so of air stream, chilling air to dew point and creating stratus

 

3.  The stronger the wind the more “turbulent mixing” of warmer, drier air aloft (> 100 meters) with surface saturated air occurs on the one hand, and the greater the depth of mixing of cooling and moistening effects on the other hand.  The net effect creates a “marine layer”  (also known as the “mixed layer”) characteristically about 200 meters deep.

 

4.  As the marine layer moves onshore, conductional heating and greater turbulent mixing erodes the saturated air from beneath. Soundings taken following the motion of the air inland would show erosion of the marine layer occurs from beneath, as shown here, here and here.

 

5.  To be discussed.  Variations in the depth of the marine layer with synoptic pattern: deep, intermediate, shallow.  Southerly surges.

 

Differences of Marine Layer/Summer Stratus from Radiation Inversion/Ground Fog

 

1.  No wind speed.  As soon as you note calm or light winds, suspect that there is no mixed layer, no marine layer, and the sounding will show t – td= 0 only at the ground, with no mixed layer.

 

2.  Fall patterns can often be  a combination.