Gloom is a low level of light which is so dim that there are physiological and psychological effects. Human vision at this level becomes monochrome and the place then seems dull and depressing.
Optical and psychological effects
People describe light conditions as gloomy when the rods in their eyes take over from the cones and so their vision becomes shades of grey as they lose their colour vision. Low light of this sort is associated with depression. This association was made as far back as the 2nd century by the ancient Greek physician, Aretaeus of Cappadocia, who said, "Lethargies are to be laid in the light and exposed to the rays of the sun, for the disease is gloom."
The naturally weak daylight during winter at extreme latitudes causes winter depression. Also, weaker electrical activity is found in the retinas of depressed people, which gives them poor visual contrast so that they see the world in grey, depressing hues. A solarium or other source of bright light may be used as light therapy to treat this.
Architecture and ergonomics
Where artificial lighting is used, this has to be sufficient to not only illuminate the task area, but also provide sufficient background lighting to avoid a sensation of gloominess which has a negative effect on efficiency. If the task is challenging, such as playing cricket, then reaction times are found to increase significantly when the illumination declines to the gloom level. This is the level at which car drivers turn their lights on.
In architecture, the level of lighting affects whether a building is perceived to be gloomy. If there is little or no sunlight or view of the outdoor surroundings, then this will tend to make the building seem gloomy. As seen from the exterior, an interior which is brighter than the surrounding light level may cause the overall building to seem gloomy because the normal cues and contrasts have been upset.
In the arts, a gloomy landscape or setting may be used to illustrate themes such as melancholy or poverty. Horace Walpole coined the term gloomth to describe the ambience of great ancient buildings which he recreated in the Gothic revival of his house, Strawberry Hill, and novel, The Castle of Otranto. Characters which exemplify a gloomy outlook include Eeyore, Marvin and Old Man Gloom. The catchphrase "doom and gloom", which is commonly used to express extreme pessimism, was popularised by the movie Finian's Rainbow in which the leprechaun Og (Tommy Steele) uses it repeatedly.
Gloomy conditions may arise when low cloud cover forms a continuous overcast. This occurs annually in California where it is known as the June gloom. Anticyclones may generate a gloom if they remain stationary so causing a haze and layer of stratocumulus clouds. These tend to occur in winter in middle latitudes or over an extended period in subtropical regions.
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- Hannah Devlin (July 21, 2010), The world truly a grey place for the depressed, Evening Herald
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- Fergus W. Campbell, Susan E. Rothwell,Michael J. Perry (19 Dec 2007), Bad light stops play, Ophthalmic and Physiological Optics 7 (2): 165–167
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- Hugh Walpole, The Old Ladies
- The Oxford dictionary of allusions, 2001, p. 299
- Darren Harris-Fain (2002), British fantasy and science-fiction writers since 1960, p. 5
- Jennifer Dewey, Jeanie Puleston Fleming, Zozobra!: The Story of Old Man Gloom
- Eric Partridge, Paul Beale (1986), A dictionary of catch phrases, p. 115
- Michael Allaby (2002), "anticyclonic gloom", Encyclopedia of Weather and Climate 1, p. 34, ISBN 978-0-8160-4071-1
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