Tech A says that batteries should be charged as fast as possible. Tech B says that the ideal charging rate is the CCA divided by 70. Who is correct?

Neither A nor B

Explanation:

The charge rate of a battery is the rate at which charge is added to the battery in a given time unit. The unit of charge rate is Coulombs/second or amps

The time to charge a battery, is given by  the battery charging formula which is given as follows;

Battery charging time, t = Battery Ah(Ampere hour)/(Charging current, A)

T = Ah/A

Where;

T = Time (Hours)

Ah = The rating of the battery in Ampere Hour

A = The Current applied given in Amperes

The charging current should 10% of the Ah battery rating, such that a 120 Ah battery requires about 12 Amperes charging current

However, due to losses in the system, the current can be set at 13A

the time for charging will then be t = 120/13 = 9.23 hours

scattering of light by tiny particles in air to produce the colors we see on sky, is dependent on the following factors:

(i) wavelength of light

(ii) size of the scattering particle  

(iii) distance traveled by light through the atmosphere.

according to rayleigh's law of scattering, the amount of scattering is inversely proportional to the fourth power of its wavelength. shorter the wavelength, greater is its scattering. hence violet/blue light is scattered more than red.

sun's light is a composite light ( visible light) with wavelengths in the range 400 nm (violet) to 700 nm (red). as sunlight passes through our atmosphere, the molecules of air scatter light according to their wavelengths. during sunrise and sunset, the sun's position is below the horizon. hence light from the sun travels a greater distance in the atmosphere when compared to its position a noon.

as sunlight enters the earth's atmosphere, blue light is scattered away and at the end of its journey in the sky, only red and orange wavelengths remain in the beam.

hence at sunrise and sunset, the sky appears reddish orange.

heats surface water up