Why relative humidity is different in different places

However, another very important consideration is not only the amount of ambient moisture in a particular location, but also the amount of moisture advection and convergence which provides additional moisture to an area. If significant, these added factors help explain why rainfall totals from thunderstorms can exceed actual PW values of the air in which the storms are occurring. The movement of thunderstorms, called propagation, also is very important in determining the actual amount of rainfall in any one location.

The slower the movement of thunderstorms, the higher the rainfall potential in one area. These examples show how relative humidity can be quite misleading. In general, assuming the dewpoint or absolute humidity does not change, the relative humidity will be highest in the early morning when the air temperature is coolest, and lowest in the afternoon when the air temperature is highest.

While dewpoint is a more definitive measure of moisture content, it is the relative humidity that commonly is used to determine how hot and humid it "feels" to us in the spring and summer based on the combined effect of air temperature and humidity. This combined effect is called the " Heat Index. In the winter, there is another index we use to determine how cold our bodies feel when we are outside. This index combines the effect of the air temperature with the speed of the wind.

When it is cold outside and the wind is blowing, the wind carries away heat from our bodies faster than if the wind was not blowing. This makes it feel colder to us. Therefore, the stronger the wind is in the winter, the colder it feels to us and the lower is the wind chill index.

If the heat index is very high or the wind chill index is very low, then we must take safety measures to protect our bodies from possible effects of the weather, including heat exhaustion, sunstroke, and heat stroke in the summer, and frostbite in the winter. Please Contact Us. Please try another search. Multiple locations were found. Please select one of the following:. Location Help. News Headlines.

Cold waters due to a cold winter or upwelling of cold water combined with a warm maritime air mass read this article for more about air masses will cause a high relative humidity, with risk of fog and mist.

There is also a clear diurnal variation in the relative humidity, especially during the summer when the days are longer. This diurnal variation is more profound over land due to the larger diurnal variation of the air temperature. Dew point The dew point is an important parameter to understand in order to predict the humidity. Rain increases the humidity in the air below the rain clouds The affecting wind Strong wind speeds near the surface will create turbulence that will mix the airmass near the surface with the air just above.

Winter vs Summer Humid air during the winter typically means misty weather most of the day, with little variation in temperature and cloud cover. An offshore wind farm in good visibility In offshore locations, the temperature of the surrounding water will have a big impact on the relative humidity. Vegetation in the urban environment: microclimatic analysis and benefits. Energy Build 35, 69— Eliasson, I.

Urban-suburban-rural air temperature differences related to street geometry. Ernst, S. Hage, K. Urban-rural humidity differences. Hair, J. Multivariate Data Analysis. Henry, J. Urban and rural humidity distributions: relationships to surface materials and land use. Hilberg, S. Holmer, B. Urban-rural vapor pression differences and their role in the development of urban heat island. Jauregui, E. Urban-rural humidity contrast in Mexico City.

Kaiser, H. The varimax criterion for analytic rotation in factor analysis. Psikometrica 23, — Kuttler, W. Lee, D. Urban—rural humidity differences in London. Liu, W.

Urban-rural humidity and temperature differences in the Beijing area. Mayer, H. Spatio-temporal variability of moisture conditions within the urban canopy layer.

A study of the urban heat island of Granada. Moriwaki, R. Urban dry island phenomenon and its impact on cloud base level. Civil Eng. Oke, T. Cermak, A. Davenport, E. Plate, and D.

Viegas Dordrecht: Kluwer-Academic Publications , 81— CrossRef Full Text. Richman, M. Rotation of principal components. Robaa, S. Some aspects of the urban climates of Greater Cairo Region, Egypt. Saz, M. Influence of different factors on relative air humidity in Szeged, Hungary. Acta Climatol. The only way that happens is if water vapor condenses faster than it can evaporate. The dew point is the temperature the air must be for water to condense and evaporate at the same rate.

If the air temperature matches the dew point, then the air is exactly as saturated as it can be without condensation forming. Condensation forms when the air temperature falls lower than the dew point. Dew point is used to calculate relative humidity. Relative humidity is a percentage measurement of water vapor saturation relative to maximum saturation. In other words, relative humidity measures how close the air temperature is to the dew point.

The level of humidity varies by season. Summer is often more humid than winter because of the added moisture in the air. The answer for most people is to purchase a humidifier to add moisture to the air in the house.