CONTEMPORARY URBAN ENVIRONMENTS: Weather

It is thought that cities create their own 'dome' meaning they have their own weather. Geographers have researched and believe the 'dome' consists of their own: temperature ranges, precipiration generation and patterns, humidity, visiblity and wind speeds.

Urban Heat Island: a significantly warmer 'island' surrounded by a rural 'sea' of cooler temperatures. There are several reasons for this.

- Urban areas have lower albedo. Extensive dark surfaces e.g. tarmac absorb heat during the day and slowly release it at night.

- Large expanses of glass and steel reflect heat into surrounding streets,

- Far less vegetation in urban areas meaning less evapotranspiration. Sewage and drains remove surface water quickly so the humidity is reduced.

- Buildings 'leak' heat through poor insulation in winter and A/C pumps hot air into the streets in summer.

- Power stations, industries and vehicles generate heat.

The 'thermal gradient' is the temperature decline from urban centres to rural-urban fringe. This is around 6 degrees during summer and 2 degrees in winter.

- Precipitation - 

In order for precipitation to form, air has to rise, cool below the dew point and allow water vapour to condense.

Fog is effectively a cloud on ground level.It tends to persist and become thicker in higher pressure conditions when winds are too weak to blow them away. Fog tended to…