Sweep of cold polar air pull down Davis Straits into the Labrador Sea by major complex depression in NE Atlantic on 28 Mar 16 forms regular pattern of open cell convection. Convection patterns only became apparent with the advent of satellite meteorology, now they reach our desk tops every day.
This is cold air over relatively warmer sea surface. Convection and condensation results but there is a weight of cold air above which is subsiding over a big area and the convection mixes in with this to limit vertical extent. Air descends in the open cells of the pattern.
A search for radiosonde data in this region to check the atmospheric structure is difficult. I came up with a model ascent from Aasiaat (west coast of Greenland just to the NE of this picture). Which does show some subsidence at about 7,000ft and is consistent with the thoughts for open cell convection.