How do I calculate dew point when I know the temperature and the relative humidity? (2024)

FAQs

How do I calculate dew point when I know the temperature and the relative humidity? ›

If you are interested in a simpler calculation that gives an approximation of dew point temperature if you know the observed temperature and relative humidity, the following formula was proposed in a 2005 article by Mark G. Lawrence in the Bulletin of the American Meteorological Society: Td = T - ((100 - RH)/5.)

To calculate the dew point: Measure the temperature and relative humidity of the air. Multiply 17.625 by the temperature and divide the result by the temperature plus 243.04.

The dewpoint when the air temperature is 28°C and the relative humidity is 47% is 15.9°C.

This is 100% relative humidity. That's why we picked this temperature. For air with this amount of moisture, 52°F (11°C) is the dew point. This just means the temperature at which the air's water vapor capacity is exactly full – the temperature where relative humidity is exactly 100%.

Expert-Verified Answer

The dew point if the dry bulb temperature is 20°C and the relative humidity is 17 % is 1.6°C. Dew point is the temperature at which air becomes saturated with water vapor and begins to condense.

Relative humidity increases as the air temperature drops to the dew point or the dew point rises to the air temperature (since the humidity is relative to the air temperature). Once the air temperature and dew point meet, the air becomes saturated and the relative humidity reaches 100%.

Example 1: If the Relative Humidity (RH) is 50% and the indoor air temperature is 80°F, the dew point would be 59°F.

Answer and Explanation:

Dry bulb temperature is on the left side of the table and find 12 ∘ C . Now, the difference between the dry bulb and wet bulb temperature is (12-7=5) 5 ∘ C . Now, looking 12 ∘ C from row side and 5 ∘ C from column side, where these two temperatures meet, that point is dew point temperature.

The dew point temperature is the temperature at which air must be cooled to become saturated with water vapor. Thus, the dewpoint temperature when the relative humidity is 30% and the air temperature is 20°C is determined as 2°C.

Dew point is the temperature at which moisture will condense on a surface. No coatings should be applied unless the surface temperature is a minimum of 5°F above this point. If the air temperature is 70°F and the relative humidity is 65%. The dew point is 57°F.

Is 100 degree relative humidity at dew point? ›

A relative humidity of 100% indicates the dew point is equal to the current temperature and that the air is maximally saturated with water. When the moisture content remains constant and temperature increases, relative humidity decreases, but the dew point remains constant.

While dew point temperature is not dependent on temperature, it is dependent on pressure: the higher the pressure, the lower the dewpoint temperature.

A home should have a relative humidity of 30% to 60%. Above 60% and you have what's considered “high” humidity. Besides being less comfortable, high humidity causes a host of other problems in your home, including: Growth of fungus and mold in various parts of the home.

Td = T - ((100 - RH)/5.) where Td is dew point temperature (in degrees Celsius), T is observed temperature (in degrees Celsius), and RH is relative humidity (in percent). Apparently this relationship is fairly accurate for relative humidity values above 50%.

Figure the difference between the dry bulb and wet bulb temperature. On Table 1, locate the column, which is headed with this temperature difference. Then locate the row labeled with the appropriate dry bulb temperature. The value at the intersection of the column and row gives the dew point.

To calculate relative humidity with temperature and dew point, follow the given instructions: Measure the air temperature T, in °C. Find out the dew point temperature D_p, in °C. Calculate relative humidity RH using the formula, RH = 100 × {exp[17.625 × D_p/(243.04 + D_p)]/exp[17.625 × T/(243.04 + T)]}.

Assuming a relative humidity of 50%, the predicted wet-bulb temperature would be around 11.5°C when the dry-bulb temperature is 16°C and the dewpoint is 7°C.

The dew point temperature is the temperature at which air must be cooled to become saturated with water vapor. Thus, the dewpoint temperature when the relative humidity is 30% and the air temperature is 20°C is determined as 2°C.

The relation between humidity and temperature formula simply says they are inversely proportional. If temperature increases it will lead to a decrease in relative humidity, thus the air will become drier whereas when temperature decreases, the air will become wet means the relative humidity will increase.