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Humidity ratio (specific humidity): choose the correct basis Define humidity ratio/specific humidity as the mass of water vapour present in which reference amount? Choose the correct basis.

Difficulty: Easy

1 m³ of wet air
1 m³ of dry air
1 kg of wet air
1 kg of dry air

Correct Answer: 1 kg of dry air

Explanation:

Definition
Specific humidity (also called humidity ratio) ω is the mass of water vapour per unit mass of dry air: ω = m_v / m_a (kg/kg dry air).

Why other options are incorrect

Options A and B refer to absolute humidity (per unit volume).
Option C uses total wet-air mass; standard ω uses mass of dry air as the reference.

Final Answer
1 kg of dry air

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