Climates at (Very) Small Scales ENVS 110 10-15-2008
Influences on micro climate • Proximity to ground • Vegetation cover (e.g. grass, forest, shading) • Proximity to water • Vegetation height (e.g., surface roughness wind speed)
Local climates • Forest climates • Shading, trapping of solar energy within canopy, lower windspeeds • Influence on soil moisture, lower evaporation rates • Seasonal changes
Urban climates • Albedo • Natural vegetation concrete asphalt • Shading • Vegetation buildings of various sizes • Effect on surface winds • Surface roughness, channeling of air currents • Aerosols (pollution) • Import of thermal energy (AC’s furnaces, etc.)
Moisture in urban environments Rural • Large storage of moisture in soil, vegetation, lakes etc. • Limited release through streams, groundwater etc. • Higher relative humidity Urban • Very little moisture storage • Efficient drainage • Lower relative humidity
Climate change due to urbanization • Less sunshine due to various forms of pollution • More abundant clouds • Higher air temperatures due to albedo changes, heat retention and release, combustion etc. • More turbulent winds • Lower humidity • More intense storms due to stronger convection over built-up areas
Mesoscale (regional) climates • Often identified with distinctive geographic region (e.g., New England, California, the Mediterranean etc.) • Can approach from local (surface) conditions up to regional level, or from global scale down to regional level.
Climate Classification • Greek: polar, temperate, tropical • Classifications based on distribution of temperature and moisture • Correlations between plant life and climate • Mix of climatological and botanical terms (e.g., tundra, prairie, savanna climate) • Empiric classification schemes: similar climates based on effect of climatic conditions on humans, vegetation etc. • Numeric classification: based on large databases, statistical parameters
Köppen Classification Five major climate types: • A – Tropical rainy climates • B – Dry climates • C – Mid-latitude rainy climates, mild winter • D – Mid-latitude rainy climates, cold winter • E – Polar climates
others • Thornthwaite • Based on moisture and temperature “efficiency” • Köppen in all it’s modifications and amendments • Genetic systems • Might address underlying causes of climate conditions • Based on airmass dominance
Influence on vegetation • Vegetation depends crucially on moisture and temperature regimes • Vegetation and climate maps should be rather similar e.g., distribution of deserts, rainforests, prairies etc.
Examples: • Forests: • Require sufficient moisture, warmth tropical, temperate, boreal forests • Grasslands: • Dominated by herbs and shrubs, drier regions • Savannaa: • Mixture of grassland and trees depending on local climate conditions • Deserts: • Very little moisture available • Tundra: • Very cold, often dry