Egwyddor mesur yr hygrometer
In the measurement method, humidity is defined as the "quantity of the physical state". The humidity referred to in daily life is relative humidity, expressed in RH percent . In short, it is the percentage of saturated water vapor (saturated water vapor pressure) in a gas (usually air) that contains the same amount of water vapor (water vapor pressure) as its air.
Mae lleithder wedi bod yn gysylltiedig yn agos â bywyd ers amser maith, ond mae'n anodd ei fynegi mewn maint. Mae yna leithder absoliwt, lleithder cymharol, pwynt gwlith, cymhareb lleithder i nwy sych (pwysau neu gyfaint) ac yn y blaen.
