why does the sun's surface much less hotter than its atmosphere?

Answer 1

Good question. The sun accelerates high energy protons and electrons that pass through the atmosphere. The particles have a much higher velocity than the surface mean thermal speed, so collisions with the atmospheric particles heats it up to a higher temperature. The particles are accelerated by time varying magnetic fields that engulf the sun caused my heat driven convection within the sun. After the particle leave the sun completely, they become the solar wind. The details are controversial (ref).

Answer 2

Because the sun isn't powered from within via convection, as was thought. That model is all but worthless. Neutrino counts are FAR too low for the "nuclear furnace" theory.

Time for a newer better theory: The sun is a giant electric discharge in space, powered externally, kind of like an anode / cathode.

The sun does things exactly the same way we do things on earth to create fusion. Particles are accelerated in a giant ring of magnetic energy (around the corona). Internal fusion just isn't supported by mounting evidence (insides cooler than outside, neutrino count too low, changes on the surface that happen WAY too fast for a "convection" model to account for, etc. etc.).

http://www.thunderbolts.info/tpod/2005/arch05/050309solar.htm
http://thunderbolts.info/tpod/2005/arch05/051013sunspot.htm
http://thunderbolts.info/tpod/2005/arch05/050517fusion.htm
http://thunderbolts.info/tpod/2005/arch05/050906solarpower.htm
http://thunderbolts.info/tpod/2006/arch06/060414sunspots.htm
http://thunderbolts.info/tpod/2006/arch06/060418penumbra.htm
http://thunderbolts.info/tpod/2005/arch05/050427sun.htm
http://thunderbolts.info/tpod/2005/arch05/051201protonstorm.htm
http://thunderbolts.info/tpod/2005/arch05/051123iron-sun.htm
http://thunderbolts.info/tpod/2006/arch06/060120solar1.htm
http://thunderbolts.info/tpod/2006/arch06/060123nebula.htm
http://thunderbolts.info/tpod/2006/arch06/060124solar3.htm
http://thunderbolts.info/tpod/2006/arch06/060126solar4.htm

Requires a bit of a MASSIVE rethink of current stallar and cosmological theory, but that's the way the science experiment crumbles! Makes more sense that inventing newer more exotic interactions between particles that simply don't do what the gravity-only model expects them to do, and throwing in dark matter, dark energy, quasars, pulsars, and black holes, etc. The phenomena observed that required these horrendous anomale-like suppositions can be much more easily explained via electrical/magnetic phenomena.

http://thunderbolts.info/tpod/2006/arch06/060602plasma-galaxy.htm
http://thunderbolts.info/tpod/2005/arch05/050415milkyway.htm
http://thunderbolts.info/tpod/2006/arch06/060721neutronstar.htm