3. Scale of microclimate
• To a botanist, Microclimate can be of a single plant leaf, with its
temperature and moisture conditions, its population of insects
and micro organisms, on the scale of a few centimetres.
• To an urban geographer, micro climate may mean the climate
of a whole town.
• SITE CLIMATE: Climate of the area available and is to be used for
the given purpose, both in horizontal extent and in height.
• The task of the designer is to take advantage of the favourable
and mitigate the adverse characteristics of the site and its
climatic features
7. AIR TEMPERATURE
• The air temperature near the ground is dependent on heat
gained/lost by the earth surface.
• heat exchange varies with day/night, season, time of the year,
latitude and cloud cover.
• During the day, with the heating of the earth surface, the air
nearest to the ground(within 2 metres) gains most temperature.
At night, the direction of heat flow is reversed.
•
TEMPERATURE INVERSION
• The phenomenon of decreasing temperature with increase in
altitude.
• Cold air tends to settle in the deepest depressions and behaves
as a liquid. It does not flow quite readily like water but like a
highly viscous liquid.
• A difference of 7‐8 m in height can cause 5‐6 deg drop in temp.
16. SOLAR RADIATION
• Three ways:
• Transparency of the atmosphere: Cloud formation, air
pollution, smog, smoke, dust, etc. affect the intensity of solar
radiation on the horizontal plane.
• Slope and orientation of the site: Intensity on the actual
ground surface. At mid latitudes, a site sloping towards the
pole will receive much less radiation than the site sloping
towards equator. (Effect is negligible around equator)
• Obstructions like hills, trees, existing buildings which may cast
a shadow on the site. The effect is most pronounced wen the
objects like on east or west of the site.
26. URBAN CLIMATE
• Man‐made environments create micro climate of their own
deviating from the regional climate. The factors causing
deviation:
• Changed surface qualities: (pavements and buildings) :
Increased absorbance of solar radiation, reduced evaporation.
• Buildings: Casting a shadow, acting as barriers to winds,
channelizing winds, storing heat in their mass and releasing it
at nit.
• Energy seepage: through walls and ventilation of heated
buildings
• Atmospheric pollution: Presence of solid particles in urban
atmosphere may assist in formation of fog and induce rainfall.
• Temperature can be 8 deg higher in cities tan the surrounding
country side, humidity can be reduced by 5‐10%, wind velocity
can be reduced by half.