Question

1. Suppose that the atmosphere were perfectly uniform, with a density throughout equal to that of air at 0 o C, 1.3 g L-l . (a) Calculate the thickness of such an atmosphere that would cause a pressure of exactly 1 standard atm at the Earth’s surface. (b) What are two implications for air travel?

Answer 1

(a) The atmospheric pressure is calculated using a mercury barometer. The mercury barometer is typically a glass tube about 3 feet high with one end open and the other end sealed. The tube is filled with mercury. This glass tube is upside down in a container, called the reservoir, which also contains mercury.

The barometer balance the weight of mercury in the glass tube against the atmospheric pressure. Atmospheric pressure is the weight of air in the atmosphere above the reservoir, so the level of mercury continues to change until the weight of mercury in the glass tube is exactly equal to the weight of air above the reservoir.

P = ghρ

Here P = Atmospheric pressure (1atm = 101325 Pa), g = gravity (9.81 m/s2), ρ = density of mercury (13534 Kg/m³ or 13.534g/cm3) and h = column's height

h = P/gρ

   = 101325/13.534 x 9.81 = 763.3 mmHg

(b) Flights leads to CO2 emission causing harm to environment.