The weight per unit area of the vapour particles in the air.

A record of the fluctuation of air temperature in the same location over a periodof time.

Photosynthetically Active Radiation; approximately equivalent to visible light radiatio

The UltraViolet part of the light spectrum. having or employing wavelengths shorter than light but longer than X-rays; lying outside the visible spectrum at its violet end; "ultraviolet radiation".

The term describing water loss from plants through emission of water vapour via the leaves by transpiration – can be a major form of stress for plants. Evaporation: the process of extracting moisture; moisture becoming a vapour, Transpiration: the emission of water vapor from the leaves of plants.

Microclimate the average climatic conditions in a very localised area. Micro: extremely small in scale or scope; Climate: the weather in some location averaged over a long period of time.

Unstable flow (of a liquid or gas).

Its full name is the Beaufort wind force scale, although it is a measure of wind speed and not of force in the scientific sense. Wind force is what you feel when you try to stand up in a strong wind. Wind force is what blows the dust, bends the trees etc.

Shade levels under coloured and white fabrics are measured in PAR (photsynthetically active radiation). This is approximately equivalent to visible radiation; 100% shade is solid.A white fabric will typically have a shade level of about 7/10 of that of a black fabric of the same weave.

The ordered array of the components of light. The colour of the fabric influences the colour (or spectrum) of the light that is absorbed, and hence the spectrum “seen” by the plants. Black fabrics absorb all light equally. White and "clear" fabrics have a reduced effect on the ultra-violets, but a similar effect to black on the infra-reds.