Cecil Moore wrote:
To the best of my
knowledge, there is no such thing as instantaneous
irradiance.

The definition of irradiance is the "average energy
per unit area per unit time". Any deviation away
from "average energy per unit area per unit time"
when discussing what I have said is a straw man
diversion, not in the spirit of a good will
discussion.
--
73, Cecil http://www.w5dxp.com