Climates at (Very) Small Scales ENVS

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