What Wet-Bulb Temperature describes
Approximate psychrometric wet-bulb temperature from Celsius temperature and relative humidity.
Wet-bulb temperature reflects evaporative cooling potential. This page uses an empirical approximation designed for common near-surface conditions rather than solving a complete psychrometric equation. Its value comes from a defined weather record rather than from the title alone, so the source interval and location should travel with the answer.
The visible input set for Wet-Bulb Temperature is air temperature, relative humidity. Before entering them, decide whether the record represents an observation, a forecast scenario, or a historical comparison. That choice changes how approximate wet-bulb temperature should be described even though it does not change the arithmetic.
Choosing observations for Wet-Bulb Temperature
Temperature and humidity must be simultaneous and representative. Humidity sensor error becomes especially important in very moist conditions, where a small difference separates air temperature, dew point, and wet bulb.
A reproducible Wet-Bulb Temperature record retains the station or sensor identifier, observation time, time zone, height or exposure when relevant, and any quality flag. Without that context, the number can look precise while describing the wrong interval or place.
Keeping the weather record auditable
Save the raw observations as well as the displayed approximate wet-bulb temperature. Record conversions, rounding, missing-data treatment, and the reason this calculation was performed so another person can reproduce it without guessing.
Create a new dated Wet-Bulb Temperature result when the location, observation window, instrument, formula convention, or source value changes. Overwriting the earlier calculation removes the evidence needed to explain a later difference.
Units, signs, and sensible magnitude
Wet-Bulb Temperature reports °C. Carry the input units through the formula and preserve the sign when it communicates direction. Converting only one entry can produce a plausible-looking but unusable result.
Estimate the order of magnitude of approximate wet-bulb temperature before accepting the display. A relevant boundary case—equal temperatures, zero duration, the selected base, or a calm condition where permitted—can expose a reversed subtraction or misplaced factor.
Sensitivity to the least certain input
Identify the observation with the greatest uncertainty and rerun the calculation at credible low and high values. The spread shows whether measurement quality could change the practical interpretation of approximate wet-bulb temperature.
Do not present the Wet-Bulb Temperature sensitivity range as a confidence interval unless input uncertainty was estimated statistically. This is a controlled check of the formula, not a probability forecast.
From Wet-Bulb Temperature, a connected temperature question can be explored with the Atmospheric Lapse Rate Calculator.
What the Wet-Bulb Temperature result leaves out
The approximation has a limited temperature and humidity domain and assumes ordinary atmospheric pressure. Use a pressure-aware psychrometric method or calibrated instrument for engineering, research, or safety-critical work.
Wet-Bulb Temperature supplies transparent arithmetic, not a forecast, warning, diagnosis, engineering certification, or permission to enter hazardous conditions. Current official information and the rules governing the activity take priority.
Reading the calculated Approximate wet-bulb temperature
The approximate wet bulb should normally fall at or below the dry-bulb temperature and above the dew point. That ordering offers a useful reasonableness check when all three values are available.
Compare approximate wet-bulb temperature with a relevant observation, forecast, normal, or operating threshold selected before using Wet-Bulb Temperature. Choosing the benchmark afterward can exaggerate an ordinary difference.
A reproducible example and independent check
The starting values shown in the form provide a complete test case. Calculate them once by hand with Stull approximation from air temperature and relative humidity, then change one input whose effect is predictable and confirm that the answer moves in the expected direction.
After testing Wet-Bulb Temperature, replace every sample value with one internally consistent weather record. Reset restores this demonstration; it does not retrieve data from an external weather service.
Using Approximate wet-bulb temperature in context
One Wet-Bulb Temperature value establishes a weather summary, not a trend. Repeated results become comparable only while their collection and calculation methods remain aligned.
When approximate wet-bulb temperature feeds another model, transfer its unrounded value together with units and assumptions. Round only at the reporting stage and only as finely as the source observations support.
Time and location boundaries for Wet-Bulb Temperature
Define where the Wet-Bulb Temperature observation applies and when its interval begins and ends. Local terrain, shade, surface type, urban development, elevation, and distance from water can create real temperature differences over short distances.
If the intended decision concerns another site, avoid treating the nearest available station as automatically representative. Document the distance and exposure difference beside approximate wet-bulb temperature and explain why the source is suitable.
From Wet-Bulb Temperature, a connected temperature question can be explored with the Temperature Change Rate Calculator.
The working rule behind Approximate wet-bulb temperature
The page applies Stull approximation from air temperature and relative humidity. Only the visible entries participate in the calculation; it does not silently retrieve a station observation, forecast, elevation, or climate normal.
For Wet-Bulb Temperature, keep intermediate precision until the final display. If another source uses a different formula or convention, label both methods before comparing their answers.
Checking Approximate wet-bulb temperature
What does Wet-Bulb Temperature calculate?
It calculates approximate wet-bulb temperature from the entries and the displayed rule, reporting °C.
Can I enter forecast values?
Yes, but label the Wet-Bulb Temperature result as a scenario. Do not mix a forecast input with an observation without documenting the difference.
Why might another source give a different answer?
Another Wet-Bulb Temperature source may use a different observation interval, station, rounding rule, threshold, formula variant, or unit convention.
How should I check the result?
Repeat Stull approximation from air temperature and relative humidity independently, keep full intermediate precision, and test one input change with an obvious direction.