Also, fans raise air temp by a small amount, due to friction, and any evaporation

lowers it. Clear?

"Lumps" of fluid matter, (think of a drop of water), through surface tension, tends to round up.

Stars and planets are or were molten or gaseous lumps of fluid and react to surface tension

to become mainly spherical. Surface irregularities remaining post-solidification are subject to

gravitational effects (as well submitted by Bob/PKB) further "flattening" that surface.

Well, that's how it appears to me.