Normal atmospheric pressure is 1.013 105 pa. the approach of a storm causes the height of a mercury barometer to drop by 27.1 mm from the normal height. what is the atmospheric pressure? (the density of mercury is 13.59 g/cm3.)

The atmospheric pressure is .

Explanation:

Given that,

Atmospheric pressure    

drop height h'= 27.1 mm

Density of mercury

We need to calculate the height

Using formula of pressure

Put the value into the formula

We need to calculate the new height

We need to calculate the atmospheric pressure

Using formula of atmospheric pressure

Put the value into the formula

Hence, The atmospheric pressure is .

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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.