What is the definition of solar max?

Answer 1

Solar maximum or solar max is a normal period of greatest solar activity in the 11 year solar cycle of the Sun. During solar maximum, large numbers of sunspots appear and the sun's irradiance output grows by about 0.1%.[1] The increased energy output of solar maxima can impact global climate and recent studies have shown some correlation with regional weather patterns.

At solar maximum, the Sun's magnetic field lines are the most distorted due to the magnetic field on the solar equator rotating at a slightly faster pace than at the solar poles. The solar cycle takes an average of about 11 years to go from one solar maximum to the next, with an observed variation in duration of 9 to 14 years for any given solar cycle.

Large solar flares often occur during a maximum. For example, the Solar storm of 1859 struck the Earth with such intensity that the northern lights could be seen as far south as Rome, approximately 42° north of the equator.