how and why does the average surface pressure features shift from summer to winter?

Answer 1

The change in the average surface pressure from summer to winter is due to the apparent movement of the sun from the Northern Hemisphere to the Southern Hemisphere.As low and high pressure areas are produced due to the differential heating of the earth's surface(land or sea) by the solar radiation,the inclination of the sun's rays plays an important part in determining the surface pressure . This pressure value shifts with the movement of the sun.