The development and progression of the weather
follow physical laws, which accounts for the frequently quick
temporal changes in the state of the atmosphere.
Climate, on the other hand, is defined as the
average state of the atmospheric weather conditions and their
fluctuations at a specific location. The geographical situation,
the elevation of the location, and the distance to large water
surfaces are all deciding influences. Climate is described by
the climatic elements of air temperature, humidity,
precipitation, air pressure, wind, cloudiness, and radiation.
One can see from these conceptual definitions
that "the climate" cannot be quantified by specific
magnitudes. At most, only measurements, observations, and
evaluations related to specific aspects of the climate can be
recorded. The Academy for Spatial Research and Land Planning has
published meteorological terminology for regional plans
(Schirmer, 1988). Bioclimatology (the effects of climate upon
humans) has also attempted to connect various climatic elements
to one another and to evaluate them subjectively. One such
example is the concept of the thermal burden ("heat
index"), developed from the combination of air temperature,
humidity, and radiation.
One of the main tasks of climatology lies
synthesizing all climatic elements under consideration of their
respective dependencies and external influences (such as
topography, relief, and the built environment).
Notwithstanding frequently time- and
cost-intensive measurements, virtually anyone can recognize and
in part assess climatic details through simple observations in
the natural realm. Examples include the observation of smoke
movements as indications of wind direction and atmospheric
temperature gradation, the observation of vegetation and its
development as gauges for the levels of temperature and
precipitation, and noting areas of ground fog cover as an
indication of local cold air pockets. Also to be mentioned are
the observation of frost damages and local cloud development.
Although climate is largely dependent upon
natural features in rural areas, a different climate is produced
by the built environment in urban areas – the urban climate.
Today, the term "urban climate" also encompasses the
change in the natural composition of the air through
anthropological influences (air pollution and aerosols).
Every structure has an influence upon the
individual climatic elements. Large built-up areas divorce
themselves in a climatic sense from their surrounding landscape.
The significant causes contributing to the production of a
separate urban climate lie in the far-reaching alteration of the
heat budget and the local wind field. The city air’s strong
saturation with particles from fires, traffic, industry, and
powerplants also is a factor. The character of a typical urban
climate is first and foremost dependent upon the size of the
city, but is also influenced by the topography, urban form, and
the proportion of open space.
Although there are elements of the urban
climate that differentiate themselves very little based on the
location in the city (such as sunlight and precipitation), other
climatic elements – affected by the heat retention capacities
of buildings, by the soil capping, by altered water budgets, and
by heat discharges – show substantial spatial variation (such
as temperature and wind patterns). Small spatial variations can
be found in areas of buildings, streets, and green spaces.