Climatology of Chicago Area Urban-Rural Differences in Humidity

Abstract:Urban/rural humidity differences were analysed by means of a climate station pair in Krefeld (51°20 N, 6°33 E), Germany, during the period from 11/2001 to 10/2002, on the basis of hourly averages of water vapour pressure. Focus was put upon on the examination of frequency, timing and duration of the Urban Moisture Excess (UME) ( e u−r > 0 hPa). It was found that the urban site was more humid (0 hPa < e u−r ≤ 0.5 hPa; weak UME) in 31.4% of the cases investigated and was only rarely significantly more humid ( e u−r > 0.5 hPa; intense UME) in 4.6%. Weak and intense UME occur during every month of the year with different frequencies per month. A diurnal course of UME was found for summer but not for winter. Weak and intense UME events show frequency maxima in the second half of the night. Most of them are characterized by durations of 1 hour, in few cases several hours duration were observed for weak (up to 14 h) and intense UME (up to 12 h).The main reason for formation of UME events might be that the surface dew point at the rural station was reached more often, earlier and lasted longer in comparison to the urban environment.

“…Attention was put upon the detection of the UME, a term, that was apparently invented by Ackerman (1987). The authoress characterized higher urban humidity as the 'urban excess'.…”

Section: Literaturementioning

confidence: 83%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Urban/rural atmospheric water vapour pressure differences and urban moisture excess in Krefeld, Germany

Kuttler

Weber

Schonnefeld

et al. 2007

“…HA AND S.-S. LEE area, but the vapor pressure of an urban area is higher, and that these characteristics are represented in monthly averages reasonably well. On the other hand Ackerman (1987), reported that the vapor pressure of an urban area during the day is usually lower than that of a rural area. This supports the view that the characteristics of an urban effect obtained by observation data collected for a short period is not representative of overall climate change.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the urban effect of long‐term relative humidity and the separation of temperature and water vapor effects

Um¹,

Lee

2007

Abstract:Monthly relative humidity values for the period between 1905 and 2003 for Busan and Seoul were used to quantify the impact of urbanization on changes in the humidity in an urban area. In this study, the urban effect on observed relative humidity was separated into water vapor and temperature effects using observations in large urban areas and rural sites. The double-station Evaluation (DSE) is a method that directly compares an urban (Busan) with rural (Miryang) sites. To estimate the urban effect in Seoul, the intermediate (Incheon) and rural (Suwon) stations were used for multistation evaluation (MSE) method. To quantify the urban effect, we assumed that observations in urban areas were influenced by macro-scale, local and urban scales. Observations from the rural sites did not include the influence of urban areas. Natural variability in the urban areas was derived by assuming that climatic conditions changed simultaneously in the early period of data collection. The sum of the temperature and water vapor effects might not be responsible for the total urban effect owing to errors.The relative humidity of Seoul has continuously decreased over the long term except for a few short periods, and the urban effect in Seoul increased with the temperature effect in the 1970s. In Busan, the urban effect increased rapidly with the water vapor effect after the early 1980s. However, urban effects in both areas have decreased in the past few years. This might be due to changes in land-use as urbanization developed. The influence of water vapor has decreased after dramatic increases in the 1970s and 1980s, which may be due to the production of excess water vapor due to lifestyle changes.

“…The urban-industrial/rural humidity differences are strongly affected by the degree of urbanization at the five districts. This result agrees well with the findings of others (Hage, 1975;Landsberg, 1981;Ackerman, 1987;Adebayo, 1987b;Lee, 1991;Jauregui and Tejeda, 1997;Unkasevic et al, 2001). 4.5.…”

Section: Resultsmentioning

confidence: 99%

Some aspects of the urban climates of Greater Cairo Region, Egypt

Robaa

2013

Rapid urbanization and industrialization over Greater Cairo Region (GCR), Egypt, have resulted in sharp land cover changes. Urban change not only impacts on land cover but also on urban climate. Detailed studies on the effect of urbanization and industrialization processes on climatic elements in GCR have been performed in this study. Five different districts were selected to represent rural, suburban, urban and industrial areas in GCR. The data of monthly mean values of minimum, maximum and mean temperatures, wind speed, relative humidity, cloud amount and rainfall amounts for the period were used. The results revealed that, for each district, whenever urbanization and/or industrialization increase, the values of minimum, maximum and mean temperatures increase while the values of wind speed, relative humidity, cloud amount and rainfall amounts decrease. The effects of industrialization processes on the climatic elements were found stronger than the effects of urbanization processes. The greatest urban-rural climatic differences were found to be 5.9, 3.1, 3.9 • C, 3.6 kt, 13.9%, 1.1 octas and 7.0 mm for the minimum, maximum and mean temperatures, wind speed, relative humidity, cloud amount and rainfall amounts, respectively, while the greatest industrial-rural climatic differences were found to be 6.7, 4.3, 4.4 • C, 4.4 kt, 17.6%, 1.7 octas and 8.0 mm for the minimum, maximum and mean temperatures, wind speed, relative humidity, cloud amount and rainfall amounts, respectively.