JAMES THOMAS

Clippings to read, watch and listen

Archive for February 2011

Two Guns

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Two Guns ghost town, Arizona

image: Big American Night

Written by James Thomas

26/02/2011 at 18:07

Posted in 004/ Environment

‘Detroit Wild City’, Florent Tillon

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Written by James Thomas

15/02/2011 at 08:36

Posted in 001/ Archi Spatial

Microclimate

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Wikipedia:

A microclimate is a local atmospheric zone where the climate differs from the surrounding area. The term may refer to areas as small as a few square feet (for example a garden bed) or as large as many square miles (for example a valley). Microclimates exist, for example, near bodies of water which may cool the local atmosphere, or in heavily urban areas where brick, concrete, and asphalt absorb the sun’s energy, heat up, and reradiate that heat to the ambient air: the resulting urban heat island is a kind of microclimate.

Another contributing factor to microclimate is the slope or aspect of an area. South-facing slopes in the Northern Hemisphere and north-facing slopes in the Southern Hemisphere are exposed to more direct sunlight than opposite slopes and are therefore warmer for longer.

The area in a developed industrial park may vary greatly from a wooded park nearby, as natural flora in parks absorb light and heat in leaves, that a building roof or parking lot just radiates back into the air. Advocates of solar energy argue that widespread use of solar collection can mitigate overheating of urban environments by absorbing sunlight and putting it to work instead of heating the foreign surface objects.[citation needed]

A microclimate can offer an opportunity as a small growing region for crops that cannot thrive in the broader area; this concept is often used in permaculture practiced in northern temperate climates. Microclimates can be used to the advantage of gardeners who carefully choose and position their plants. Cities often raise the average temperature by zoning, and a sheltered position can reduce the severity of winter. Roof gardening, however, exposes plants to more extreme temperatures in both summer and winter.

Tall buildings create their own microclimate, both by overshadowing large areas and by channelling strong winds to ground level. Wind effects around tall buildings are assessed as part of a microclimate study.

Microclimates can also refer to purpose made environments, such as those in a room or other enclosure. Microclimates are commonly created and carefully maintained in museum display and storage environments. This can be done using passive methods, such as silica gel, or with active microclimate control devices.

San Francisco is a city with microclimates and submicroclimates. Due to the city’s varied topography and influence from the prevailing summer marine layer, weather conditions can vary by as much as 9°F (5°C) from block to block. [1]

The region as a whole, known as the San Francisco Bay area can have a wide range of extremes in temperature. In the basins and valleys adjoining the coast, climate is subject to wide variations within short distances as a result of the influence of topography on the circulation of marine air. The San Francisco Bay Area offers many varieties of climate within a few miles. In the Bay Area, for example, the average maximum temperature in July is about 64 °F (18 °C) at Half Moon Bay on the coast, 87 °F (31 °C) at Walnut Creek only 25 miles (40 km) inland, and 95 °F (35 °C) at Tracy, just 50 miles (80 km) inland. [2]

The Los Angeles and San Diego areas are also subject to phenomena typical of a microclimate. As such, the temperatures can vary as much as 18°F (-8°C) between inland areas and the coast, with a temperature gradient of over one degree per mile (1.6 km) from the coast inland. Southern California has also a weather phenomenon called “June Gloom or May Grey”, which sometimes gives overcast or foggy skies in the morning at the coast, but usually gives sunny skies by noon, during late spring and early summer.

Calgary, Alberta is also known for its microclimates. Especially notable are the differences between the downtown and river valley/flood plain regions and the areas to the west and north. This is largely due to an elevation difference within the city’s boundaries of over 1000 ft, but can also be attributed somewhat, to the effects of the seasonal Chinooks. [3]

Halifax, Nova Scotia also has numerous microclimates. Coastal temperatures and weather conditions can differ considerably from areas located just 5-15km inland. This is true in all seasons. Varying elevations are common througout the city, and it is even possible to experience several microclimates while travelling on a single highway due to these changing elevations.

Santiago, Chile is also subject to microclimates, but is not as well known for it.

Known for its wines, the Ticino region in Switzerland benefits from a microclimate in which palm trees and banana trees grow.

Gran Canaria is called “Miniature Continent” for its rich variety of microclimates.

Written by James Thomas

08/02/2011 at 16:51

Posted in 004/ Environment

Microscale Meteorology

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Wikipedia:

Microscale meteorology is the study of short-lived atmospheric phenomena smaller than mesoscale, about 1 km or less.[1] These two branches of meteorology are sometimes grouped together as “mesoscale and microscale meteorology” (MMM) and together study all phenomena smaller than synoptic scale; that is they study features generally too small to be depicted on a weather map. These include small and generally fleeting cloud “puffs” and other small cloud features.[2] Microscale meteorology controls the most important mixing and dilution processes in the atmosphere.[3] Important topics in microscale meteorlogy include heat transfer and gas exchange between soil, vegetation, and/or surface water and the atmosphere caused by near-ground turbulence. Measuring these transport processes involves use of micrometeorological (or flux) towers. Variables often measured or derived include net radiation, sensible heat flux, latent heat flux, ground heat storage, and fluxes of trace gases important to the atmosphere, biosphere, and hydrosphere.

Written by James Thomas

08/02/2011 at 16:44

Posted in Uncategorized