Ash Wednesday
The first day of Lent in the Western Christian Church, marked by services of penitence, and so named from the custom of marking the foreheads of penitents with ashes on that day.
carbohydrate by difference
Historically it was difficult to determine the various carbohydrates present in foods, and an approximation was made by subtracting the measured protein, fat, ash, and water from the total weight. ...
cinder cone
A cone formed by fragments of solidified lava thrown out during a volcanic explosion. See Cascadden et al. (1997) New Mexico Bureau of Mines, Bull. 156.
dust veil
Fine particles of ash, dust, and sulphur dioxide that are thrown up into the stratosphere by a volcanic eruption, and which can serve as condensation nuclei for the formation of sulphate aerosols.
Ember Days
Four groups each of three days, namely the Wednesday, Friday, and Saturday after St Lucy (13 Dec.), the first Sunday in Lent, Whitsunday, and Holy Cross Day (14 Sept.) respectively, which have been ...
Entisols
Embryonic mineral soils, including those that have no distinct pedogenic horizons. Representing only the initiation of soil-profile development, entisols are common on recent flood plains, steep ...
fallout
Solid material that falls to the ground from the sky, including radioactive debris that falls after a nuclear explosion, and volcanic ash that falls after a volcanic eruption.
fly ash
Large solid particles that are contained in emissions from fuel combusted in a furnace and emitted with the smoke plume unless trapped by a dust separator or baffle chamber.
ignimbrite
A pyroclastic flow deposit that contains material varying in size from ash to pumice clasts; it may be unconsolidated or cemented.
incineration
Controlled burning of domestic or industrial waste, widely used as a method to dispose of waste. This is preferably done in a furnace or stove to maximize efficient combustion and minimize the volume ...
Krakatoa
A small volcanic island in Indonesia, lying between Java and Sumatra, scene of a great eruption in 1883 which destroyed most of the island.
pyroclastic flow
A hot, dense mixture of ash, pumice, rock fragments, and gas that is formed during an explosive volcanic eruption and flows downhill at great speed.
Shrove Tuesday
The day immediately before Ash Wednesday, so named from the ‘shriving’, i.e. confession and absolution, of the faithful on that day.
Tilaka
A mark applied principally to the forehead, but also on occasion to other parts of the body, with a paste made from a colouring substance, such as sandalwood or ash. Its significance depends on the ...
water in the liturgy
According to common belief, the four elements that form the universe are earth, fire, air and water. None of these elements is so rich in symbolism as water, closely linked ...
