HUMIDITY RULE COPIED!

Relative Humidity

Actual Vapor Pressure
Saturation Vapor Pressure
RH = (e / es) × 100%
Concept: The ratio of water vapor present in the air to the maximum amount it can hold at that temperature.

Relative Humidity Guide

RH
Rel. Humidity

The ratio of moisture in the air compared to the maximum it can hold.

e
Vapor Pressure

The actual pressure exerted by the water vapor currently in the air.

es
Saturation

The maximum vapor pressure possible at a specific temperature.

/
The Ratio

Shows how "full" the air is with moisture relative to its capacity.

100%
Percentage

Converts the decimal ratio into a standard percentage for easy reading.

Td
Dew Point

The temperature at which RH reaches 100% and condensation begins.

Evolution of Humidity Science

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1450 AD | NICHOLAS OF CUSA

The first hygrometer was surprisingly simple: a large ball of wool. Cusa realized that wool absorbs moisture from the air, so he weighed the wool on a scale. When the wool got heavier, the air was more humid!

1480 AD | DA VINCI'S REFINEMENT

Leonardo da Vinci improved the wool-scale design. He created a mechanical version that could more accurately track the changes in weight, proving that "invisible" water vapor was a measurable physical property.

1783 AD | HORACE SAUSSURE

Saussure invented the "Hair Hygrometer." He discovered that human hair stretches when it’s damp and shrinks when it’s dry. This method was so effective it was used in weather stations for over a century.

"Did you know? The most accurate hair for hygrometers was historically considered to be 'blonde, fine, and chemically untreated'—often sourced from specific regions in Europe for its consistent elasticity!"

Humidity Science Challenge ☁️

Test your knowledge on Dew Point, Relative Humidity & Psychrometry!