[Ref Pilot’s Handbook of Aeronautical Knowledge, FAA-H-8083-25B Page 12-7]

Q: What’s the difference between flying over land/pavement/continent and over water at daytime?

A: the convective currents cause turbulent

 

Convective currents

Convective currents cause the bumpy, turbulent air sometimes experienced when flying at lower altitudes during warmer weather.

 

Pavement / Land releasing heat wave cause updrafts

Water bodies/Vegetation like a group of trees absorbing hear cause downdrafts

 

Rightly, convective currents cause the local wind circulation – sea breeze (day), land breeze (night).