The longitude (abbreviation: Long., Î», or lambda) of a point on the Earth's surface is the angle east or west from a reference meridian to another meridian that passes through that point. All meridians are halves of great ellipses (often improperly called great circles), which converge at the north and south poles.
Use the dual thermometers to calculate relative humidity. Fisher Scientific Mason's Hygrometer has one dry thermometer and one wet thermometer which provide temperature readings for determining the relative humidity.
In term of equipment: One device is known as a hygrometer. A hygrometer is used tomeasure humidity. Not to be confused with the hydrometer which measures the specificgravity of liquids. A Psychrometer is a type of Hygrometer.