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Dew Point Calculator

Calculate the dew point temperature.

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Dew Point Calculator
Calculate the dew point temperature.

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Understand Air Saturation and Comfort

The dew point is the temperature to which air must be cooled to become saturated with water vapor. When cooled further, the airborne water vapor will condense to form liquid water (dew). This calculator uses a common approximation of the Magnus formula to find the dew point based on the current air temperature and relative humidity. It's a useful metric for meteorology and understanding human comfort levels.

The Dew Point Formula Explained

A widely used approximation is: Td = (b * α(T, RH)) / (a - α(T, RH)) Where:

  • Td is the dew point temperature.
  • T is the temperature and RH is the relative humidity.
  • α(T, RH) = (a * T / (b + T)) + ln(RH / 100)
  • a and b are constants (a = 17.27, b = 237.7 °C).

How to Use the Calculator

  1. Temperature (°C): Enter the current air temperature in Celsius.
  2. Relative Humidity (%): Enter the current relative humidity.
  3. Calculate: The tool will display the calculated dew point temperature in Celsius.

Real-World Example

The air temperature is 25°C and the relative humidity is 60%.

  • The calculator will show that the dew point is approximately 16.7°C.
  • This means that if the temperature drops to 16.7°C, dew will start to form on surfaces.

Frequently Asked Questions (FAQ)

  • What does a high dew point mean? A high dew point means there is a lot of moisture in the air. This is what makes hot weather feel 'muggy' or 'sticky', because your sweat does not evaporate easily.
  • How does dew point relate to human comfort?
    • Dew points below 10°C (50°F) feel dry and comfortable.
    • Dew points between 16-20°C (60-68°F) feel 'sticky' or 'muggy'.
    • Dew points above 21°C (70°F) are generally considered oppressive.
  • Is dew point the same as relative humidity? No. Relative humidity is a percentage that depends on the temperature. Dew point is an absolute measure of how much moisture is in the air. A cold day with 100% humidity feels much different than a hot day with 100% humidity because the dew points are different.