Thunder and Lightening

Intense psychological experiences can come from situations where landscape, light and weather interact. They are found in ambitious installations such as  the LandArt projects from the 1970s, which were created in the deserts of south west USA by the artist Walter de Maria, who died last week.

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He was influenced by the outright absurdity of Dada, and wanted people to be moved by “the vast and actual spaces of America” for which he created installations such as Lightening Field in New Mexico. Extremes in weather are common in the deserts there and storms are part of the landscape. The work comprises 400 vertical stainless steel poles 20 feet apart spread over a field measuring 1 mile by 1 kilometre.

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The poles take currents of many thousand amps between charged clouds of ionised air and the ground. The lightening flashes occur at the moment when the charges equalise, only to build up different amounts of ionised air once again, depending on the different moisture contents and temperatures.

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This is the time of year for frequent thunder storms in much of the northern hemisphere. They are caused by the rapid upward movement of moist warm air. As it moves upwards it gets cooler and so the moisture condenses to become cumulonimbus clouds.

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The water droplets get bigger and fall as rain when their temperature reaches the dew point. This is when the temperature of condensation is the same as that of evaporation, and it varies according to the atmospheric pressure.

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