Specific Humidity is measured by

Specific humidity is the mass of water vapour in a unit mass of moist air. Specific humidity is at a maximum in the tropics and declines as one moves poleward reaching minimum values in each polar region.
It can be calculated using the formula:
Specific humidity $${\bf{ = 6}}{\bf{.11 \times 1}}{{\bf{0}}^{\frac{{{\bf{7}}{\bf{.5\, \times \,dew\, point}}}}{{{\bf{237}}{\bf{.3\, + \,dew\, point}}}}}}$$
Its measuring unit is g/g or, kg/kg.