Tuesday, April 30, 2013

Sylvanshine

Sylvanshine is an optical phenomenon in which dew-covered trees of species whose leaves are wax-covered retroreflect beams of light, as from a vehicle's headlights, sometimes causing trees to appear to be snow-covered at night during the summer. The phenomenon was named and explained in 1994 by Professor Alistair Fraser of Pennsylvania State University, an expert in meteorological optics. According to his explanation, the wax on the leaves causes water to form beads, which become, in effect, lenses. These lenses focus the light to a spot on the surface of the leaf, and the image of this spot is directed as rays in the opposite direction.

Monday, April 29, 2013

gegenschein

The gegenschein (German for "counter shine") is a faint brightening of the night sky in the region of the antisolar point.

Sunday, April 28, 2013

Heiligenschein


Heiligenschein (German for "aureola" , literally "saint's shine", pronounced [ˈhaɪlɪɡənˌʃaɪn]) is an optical phenomenon which creates a bright spot around the shadow of the viewer's head. It is created when the surface on which the shadow falls has special optical characteristics. Dewy grass is known to exhibit these characteristics, and creates a Heiligenschein. Nearly spherical dew droplets act as lenses to focus the light on the surface beneath them. Some of this light 'backscatters' in the direction of the sunlight as it passes back through the dew droplet. This makes the antisolar point appear the brightest.

The opposition effect creates a similar halo effect, a bright spot of light around the viewer's head when the viewer is looking in the opposite direction of the sun, but is instead caused by shadows being hidden by the objects casting them. When viewing the Heiligenschein, there are no coloured rings around the shadow of the observer, as in the case of a glory.

Saturday, April 27, 2013

glory


A glory is an optical phenomenon, appearing much like an iconic Saint's halo about the head of the observer, produced by light backscattered (a combination of diffraction, reflection and refraction) towards its source by a cloud of uniformly-sized water droplets. The association with a halo is not coincidental, but derivative, though a real glory has multiple colored rings.

Friday, April 26, 2013

Airglow


Airglow (also called nightglow) is the very weak emission of light by a planetary atmosphere. In the case of Earth's atmosphere, this optical phenomenon causes the night sky to never be completely dark (even after the effects of starlight and diffused sunlight from the far side are removed).

Thursday, April 25, 2013

afterglow

An afterglow is a broad high arch of whitish or rosy light appearing in the sky due to very fine particles of dust suspended in the high regions of the atmosphere. An afterglow may appear above the highest clouds in the hour of deepening twilight, or reflected from the high snowfields in mountain regions long after sunset. The particles produce a scattering effect upon the component parts of white light.

After the eruption of the volcano Krakatoa in 1883, a remarkable series of red sunsets appeared worldwide. These were due to an enormous amount of exceedingly fine dust blown to a great height by the volcano's explosion, and then globally diffused by the high atmospheric currents. Edvard Munch's painting The Scream possibly depicts an afterglow during this period.

Wednesday, April 24, 2013

chatoyancy


In gemology, chatoyancy, or chatoyance, is an optical reflectance effect seen in certain gemstones. Coined from the French "œil de chat," meaning "cat's eye," chatoyancy arises either from the fibrous structure of a material, as in tiger eye quartz, or from fibrous inclusions or cavities within the stone, as in cat's eye chrysoberyl. The effect can be likened to the sheen off a spool of silk: The luminous streak of reflected light is always perpendicular to the direction of the fibres. For a gemstone to show this effect best it must be cut en cabochon, with the fibers or fibrous structures parallel to the base of the finished stone. Faceted stones are less likely to show the effect well.

Gem species known for this phenomenon include the aforementioned quartz, chrysoberyl, beryl (especially var. aquamarine), tourmaline, apatite, moonstone and scapolite. Glass optical cable can also display chatoyancy if properly cut, and has become a popular decorative material in a variety of vivid colors.

Tuesday, April 23, 2013

asterism

In gemology, an asterism is an optical phenomenon displayed by some rubies, sapphires, and other gems (i.e. star garnet, star diopside, star spinel, etc.) of an enhanced reflective area in the shape of a "star" on the surface of a cabochon cut from the stone. Star sapphires and rubies get their asterism from the titanium dioxide impurities (rutile) present in them. The Star-effect or "asterism" is caused by the dense inclusions of tiny fibers of rutile (also known as "silk"). The stars are caused by the light reflecting from needle-like inclusions of rutile aligned perpendicular to the rays of the star. However, since rutile is always present in star gemstones, they are almost never completely transparent.

A distinction can be made between two types of asterism:

  • Epiasterism, such as that seen in sapphire and most other gems, is the result of a reflection of light on parallel arranged inclusions inside the gemstone.
  • Diasterism, such as that seen in rose quartz, is the result of light transmitted through the stone. In order to see this effect, the stone must be illuminated from behind.

Monday, April 22, 2013

Lustre

Lustre (or luster) is a description of the way light interacts with the surface of a crystal, rock, or mineral. The word lustre traces its origins back to the Latin word lux, meaning "light", and generally implies radiance, gloss, or brilliance.

A range of terms are used to describe lustre. Many terms refer to materials having similar lustres, such as earthy, metallic, greasy, and silky. Similarly, the term vitreous (derived from the Latin for glass, vitrum) refers to a glassy lustre. A list of these terms is given below.

Sunday, April 21, 2013

cross-thread

cross-thread:

To screw together two threaded pieces without aligning the threads correctly.

Saturday, April 20, 2013

ipse-dixitism

An ipse-dixitism or bare assertion is an unsupported or dogmatic assertion; it is a term sometimes used to point out a missing argument.

Someone guilty of perpetrating an ipse-dixitism does not explicitly define it as an axiom, and certainly not as a premise, but often appears presented in syllogistic form, as: "The economy needs more scientists, so expansion of science education will boost the future economy". The proposition rests on an ipse-dixitism unless the speaker gives reasons why "the economy needs more scientists".

Friday, April 19, 2013

Phthia

Phthia (Greek: Φθία or Φθίη; transliterations: Fthii (modern), Phthíē (ancient)) in ancient Greece was the southernmost region of ancient Thessaly, on both sides of Othrys Mountain. It was the homeland of the Myrmidones tribe, who took part in the Trojan War under Achilles.

Thursday, April 18, 2013

Cultural cringe

Cultural cringe, in cultural studies and social anthropology, is an internalized inferiority complex which causes people in a country to dismiss their own culture as inferior to the cultures of other countries. It is closely related, although not identical, to the concept of colonial mentality, and is often linked with the display of anti-intellectual attitudes towards thinkers, scientists and artists who originate from a colonial or post-colonial nation. It can also be manifested in individuals in the form of "cultural alienation". In many cases, cultural cringe, or an equivalent term, is an accusation made by a fellow-national, who decries the inferiority complex and asserts the merits of the national culture.

Wednesday, April 17, 2013

noisome

noisome (comparative more noisome, superlative most noisome)

  1. Morally hurtful or noxious.
  2. Hurtful or noxious to health; unwholesome, insalubrious.
  3. Offensive to the senses; disgusting, unpleasant, nauseous; foul, fetid, especially having an undesirable smell; sickening, nauseating.

Tuesday, April 16, 2013

nostrum

nostrum (plural nostrums or nostra)

A medicine or remedy in conventional use which has not been proven to have any desirable medical effects.

Monday, April 15, 2013

mien

mien (usually uncountable; plural miens)

  1. (uncountable) Demeanor; facial expression or attitude, especially one which is intended by its bearer.
  2. (countable) A specific facial expression

Sunday, April 14, 2013

epigone

epigone (plural epigones)

  1. A follower or disciple.
  2. An undistinguished or inferior imitator of a well known artist or their style.

Saturday, April 13, 2013

opsimath

An opsimath can refer to a person who begins, or continues, to study or learn late in life. The word is derived from the Greek οψε (opse), meaning 'late' and μανθανω (manthano), meaning 'learn'.

Opsimathy was once frowned upon, used as a put down with implications of laziness, and considered less effective by educators than early learning. The emergence of "opsimath clubs" has demonstrated that opsimathy has shed much of this negative connotation, and that this approach may, in fact, be desirable.

Friday, April 12, 2013

Thursday, April 11, 2013

Wednesday, April 10, 2013

Tuesday, April 9, 2013

captious

captious

  1. Having a disposition to find fault unreasonably or to raise petty objections.
  2. (obsolete, literary) Intended to capture or entrap.

Monday, April 8, 2013

bibulous

bibulous (comparative more bibulous, superlative most bibulous)

  1. very absorbent
  2. given to or marked by the consumption of alcohol

Sunday, April 7, 2013

tureen

A tureen is a serving dish for foods such as soups or stews, often shaped as a broad, deep, oval vessel with fixed handles and a low domed cover with a knob or handle. Over the centuries, tureens have appeared in many different forms, some round, rectangular, or made into fanciful shapes such as animals or wildfowl. Tureens may be ceramic—either the glazed earthenware called faience or porcelain—or silver, and customarily they stand on an undertray or platter made en suite.

Saturday, April 6, 2013

tricorne

The tricorne or tricorn is a style of hat that was popular during the 18th century, falling out of style by 1800. At the peak of its popularity, the tricorne was worn as civilian dress and as part of military and naval uniforms. Its distinguishing characteristic was a practical one: the turned-up portions of the brim formed gutters that directed rainwater away from the wearer's face, depositing most of it over his shoulders. Before the invention of specialized rain gear, this was a distinct advantage.

Friday, April 5, 2013

plaintive

plaintive (comparative more plaintive, superlative most plaintive)

  1. Sorrowful, mournful or melancholic.

Thursday, April 4, 2013

Wednesday, April 3, 2013

Barany chair

The Barany chair or Bárány chair, named for the Austro-Hungarian physiologist Robert Bárány, is a device used for aerospace physiology training, particularly for student pilots. The subject is placed in the chair, blindfolded, then spun about the vertical axis while keeping his head upright or tilted forward or to the side. The subject is then asked to perform tasks such as determine his direction of rotation while blindfolded, or rapidly change the orientation of his head, or attempt to point at a stationary object without blindfold after the chair is stopped. The chair is used to demonstrate spatial disorientation effects, proving that the vestibular system is not to be trusted in flight. Pilots are taught that they should instead rely on their flight instruments.

Tuesday, April 2, 2013

blag

blag

  1. (UK, informal) To obtain (something) for free, particularly by guile or persuasion.
  2. (UK, informal) More specifically, to obtain confidential information by impersonation or other deception.
    The newspaper is accused of blagging details of Gordon Brown's flat purchase from his solicitors.
  3. (UK, informal) To beg, to cadge.
    Can I blag a fag?
  4. (UK, informal) To steal.
  5. (Polari) To pick up someone.
  6. (UK, informal, 1960s) To persuade.
    He's blagged his way into many a party.
  7. (UK, informal, 1940s) To deceive, to perpetrate a hoax on.

Monday, April 1, 2013

cleanroom

A cleanroom is an environment, typically used in manufacturing or scientific research, that has a low level of environmental pollutants such as dust, airborne microbes, aerosol particles and chemical vapors. More accurately, a cleanroom has a controlled level of contamination that is specified by the number of particles per cubic meter at a specified particle size. To give perspective, the ambient air outside in a typical urban environment contains 35,000,000 particles per cubic meter in the size range 0.5 μm and larger in diameter, corresponding to an ISO 9 cleanroom, while an ISO 1 cleanroom allows no particles in that size range and only 12 particles per cubic meter of 0.3 μm and smaller (see table below).