Earth Sciences

This page covers everything about the earth and its history. It includes geology and meteorology (but see also Minerals).

Numbers

Age of the Earth (and the rest of the solar system)		4.55 billion years
Life on Earth began about		4 billion years ago
Circumference of the Earth at the Equator		24,901 m (40,074 km)
Mean diameter of the earth		7,918 m (12,743 km)
Mean radius of the earth		3,959 m (6,371 km)
Axial tilt (currently– to the nearest 0.5 degrees)		23.5°
Approximate radius of the (solid) inner core		800 m (1,300 km)
Approximate thickness of the (liquid) outer core		1,400 m (2,250 km)
Approximate thickness of the mantle		1,800 m (2,900 km)
Depth of the crust (thinnest in the ocean beds)		3 – 45 m (5 – 70 km)
Speed at which the Earth moves relative to the sun		66,250 mph
For 1,000 feet rise in altitude: temperature drops by		1o Fahrenheit
Sea water (of typical salinity) freezes at approximately		–2o C
Approximate altitude at which atmospheric pressure is about half that at sea level		3.4 miles (5.5 km) 18,000 ft (5,500m)
Fog and mist: visibility boundary (less is fog, more is mist)		1,100 yards
760 millimetres of Mercury		1 atmosphere (bar)
Depth of snow equal to 1 inch of rain		1 foot
Latitude of the Equator		0o
Latitude of the North and South Poles		+/– 90°
Longitude of Greenwich (the Prime Meridian)		0°
Longitude of the International Date Line (mainly)		180°
Latitude of the Tropics (Cancer is North, Capricorn is South)		+/– 23° 26'
Latitude of the Arctic/Antarctic circles		+/– 66° 34'

Notice that the latitudes of the tropic and the polar circles (in each hemisphere) add up to 90°.

Latitude of Lizard Point, the most southerly point of Great Britain		49° 57'
Latitude of London		51° 30' 25"
Latitude of Dunnet Head, the most northerly point of Great Britain		58° 40' 21"
Degrees of longitude in a 1–hour time zone (360 / 24)		15
Percentage of the earth's surface covered by water		71
Number of points of the compass, in European tradition		32

Types of Rock

Type of rock formed when lava cools: e.g. granite, basalt, peridotite		Igneous
Rocks that have been restructured by heat or pressure: e.g. gneiss, slate, marble, schist, quartzite		Metamorphic
Rocks formed by the deposition of the remains of other rocks or other materials, or by precipitation from solution: e.g. limestone, chalk, sandstone, shale		Sedimentary

Supercontinents

Supercontinent that existed about 250 million years ago: postulated in 1912 by the German geophysicist Alfred Wegener; the name originated in 1928 at a symposium on his work (Wegener called it "the Urkontinent")		Pangaea
About 135 million years ago, Pangaea split into		Gondwana
		Laurasia

The Atmosphere

Layers

The Earth's atmosphere has four or five layers, depending on who you ask. (NASA says four; Wikipedia says four "primary" layers and five "main" layers. Wikipedia's five layers (the distances – from the Earth's surface – are approximations) are:

From ground level, to between 7 and 11 miles	Where weather takes place; heated at lower levels by the ground, which absorbs heat from the sun, but temperature decreases with altitude. Thinner at the poles		Troposhere
10–25 miles	Heated from above by absorption of ultraviolet radiation from the Sun, which causes temperature to rise with altitude; includes the Ozone Layer		Stratosphere
25–50 miles	Temperature decreases with increasing altitude		Mesosphere
50–430 miles	Characterised by ionisation caused by ultraviolet radiation – includes most of the Ionosphere (which extends down into the upper Mesosphere). Temperatures increase with altitude due to absorption of highly energetic solar radiation by the small amount of residual oxygen still present		Thermosphere
Above 430 miles	Where the atmosphere thins out into space. Lower limit varies from about 300 miles to 600 miles; upper limit is about 6,000 miles		Exosphere

NASA doesn't mention the highest layer (not on the page cited above, anyway).

The following region includes the fourth layer and parts of the third and fifth:

60–1,000 km (37–620 miles)

The region that's ionised by solar radiation (the solar wind); starts in the upper Mesosphere, coincides with the Thermosphere. Divided into three layers, of increasing ionisation: the D–region (47–60 miles), the E–region (60–95 miles), and the F–region (95–600 miles)

Ionosphere

Gases

Most abundant gas in the atmosphere (78%)		Nitrogen
Second most abundant (21%)		Oxygen
Third most abundant (1%)		Argon

Named Winds (and Storms)

Northerly katabatic (downslope) wind of the Adriatic and neighbouring countries – name comes from the same root as the Greek word for the north wind		Bora
Hot, dry wind in the southern Australian desert in summer		Brickfielder
Strong, often persistent and dry south–easterly wind that blows from spring to late summer; believed to clear Cape Town of pollution and 'pestilence'		Cape Doctor
The warm, dry wind that blows down the eastern (inland) side of the Rocky Mountains at the end of winter – named after the native people of the north–western USA		Chinook
Cool sea breeze of summer afternoons in Western Australia		Fremantle (Freo) Doctor
Warm wind from the Sahara to the Mediterranean coast of Africa		Harmattan (Doctor)
The British Isles' only named wind: a strong north–easterly that blows down the south–west slope of Cross Fell, Cumbria (the highest summit in the Pennines)		Helm Wind
Wind that brings warm weather to Egypt and Sudan in spring (March–April)		Khamaseen (Khamsin)
Easterly wind that blows in the Western Mediterranean		Levanter
Cold, dry wind in the Mediterranean provinces of France and up the Rhone valley		Mistral
Seasonal winds on and around the Indian subcontinent; name comes from an Arabic word meaning "season"		Monsoon
The strong westerly winds found in the Southern Hemisphere, generally between the latitudes of 40 and 50 degrees		Roaring Forties
The warm, dry wind that blows onto the Mediterranean from North Africa, sometimes reaching southern Italy where it can cause 'blood rain' as it picks up moisture		S(c)irocco sirocco scirocco

The first UK storm to be officially named by the Met Office (hitting northern Scotland in 2015)		Abigail
Hurricane that devastated New Orleans (among other places) in 2005		Katrina
Tropical cyclone that caused widespread destruction in Japan in October 2019, causing some matches in the Rugby World Cup to be cancelled (a name meaning 'rapidity' or 'speed' in Tagalog, given to a Philippine comic book hero created in 1947)		Hagibis

The Beaufort Scale

The following definitions are those used by the UK Meteorological Office, which describes the Beaufort scale as "an empirical measure for describing wind intensity based on observed sea conditions".

The Met Office also gives a scale of "seastates", which is named by Wikipedia as the Douglas sea scale. The two scales don't correspond exactly, but the Met Office does align them as below; for example, a Phenomenal seastate is equivalend to a Hurricane on the Beaufort scale, even though the maximum wave heights are slightly different.

The most important thing for quizzers is to be able to relate the wind force numbers to their descriptions (for example: Force 8 is described as a Gale). Other information in the table below may come up occasionally, but I include it here mainly as background information.

The speeds are maximums (or maxima, if you prefer). For example, a wind speed of between 3 and 7 miles per hour indicates force 2. Wave heights are also maximums, in metres.

Force	Knots	mph		Description	Wave height	Seastate	Description (Douglas sea scale)
0	1	1		Calm	0	0	Calm (glassy)
1	3	3		Light air	0.1	1	Calm (rippled)
2	6	7		Light breeze	0.3	2	Smooth (wavelets)
3	10	11		Gentle breeze	1.0	3	Slight
4	16	18		Moderate breeze	1.5
						4	Moderate
5	21	24		Fresh breeze	2.5
6	27	31		Strong breeze	4	5	Rough
7	33	40		Near gale	5.5
						6	Very rough
8	40	46		Gale	7.5
						7	High
9	47	54		Strong gale	10
10	55	63		Storm	12.5	8	Very high
11	63	72		Violent storm	16
12	64+	73+		Hurricane		9	Phenomenal

Sea Areas

"The Shipping Forecast, issued by the Meteorological Office" is a familiar and comforting friend to many listeners of the BBC's Radio 4 – of whom I am one.

Some aspects of the Shipping Forecast – essentially those that refer to the broadcast rather than the weather, including the full list of areas in the order that they're read out – are covered on my Radio page.

Areas around the British coast: Cromarty, Forth, Tyne, Humber, Thames, Dover, Wight, Portland, Plymouth, Lundy, Irish Sea, Malin, Hebrides, Fair Isle

Similarly for Ireland: Lundy, Fastnet, Shannon, Rockall, Malin, Irish Sea

Two areas border the coasts of both Spain and Portugal: FitzRoy, Trafalgar

Trafalgar also touches the coast of Morocco.

Number of sea areas			31
North and South Utsire are off the coast of			Norway
Fisher is off the coast of			Denmark
German Bight is off the coast of Germany and
Areas in the North Sea, with no coast (from north to south)	Separated from the coast of Norway by North and South Utsire		Viking
	Separated from the Scottish coast by Forth and Cromarty		Forties
	Separated from the English coast by Tyne		Dogger
Areas in the Atlantic, with no coast	Off south–west England; bordered by Shannon and Fastnet to the north, FitzRoy to the south		Sole
	Off north–west Scotland, north of Rockall; named after a sandbank		Bailey
Most northerly area, most westerly, and last to be mentioned			South East Iceland
Most southerly			Trafalgar
The Channel Islands are in			Portland

 

Orkney and Shetland are in		Fair Isle
The only one that's named after a person (the founder of the Meteorological Office)		FitzRoy
Renamed FitzRoy in 2002 to avoid confusion with the Spanish area of the same name		Finisterre
Introduced in 1955 when Dogger was split in two		Fisher
German Bight was known, until 1956, as		Heligoland
Merged with Hebrides around 1982		Minches
Introduced in 1984 to co–ordinate with Norwegian forecasts – formerly part of Viking		North & South Utsire

There's more information, including an interactive map (check out the red areas for gale warnings) here on the Met Office's web site.

Climate Treaties

1997: established legally–binding obligations for developed countries to reduce their greenhouse gas emissions in the period 2008–2012		Kyoto Protocol
2012: amended the Kyoto Protocol to cover the period 2013–2020 (but never came into force)		Doha Amendment
2015: governs emission reductions from 2020; came into force on 4 November 2016		Paris Agreement

Other

Shapes that indicate a warm front, on a weather map		Semi–circles
Shapes that indicate a cold front, on a weather map		Triangles

Caused by the reaction of sulphur dioxide and nitrogen oxide with water molecules in the atmosphere		Acid rain
Area of high atmospheric pressure		Anticyclone
The Greenwich Meridian crosses the Equator in (i.e. 0° latitude & 0° longitude)		(South) Atlantic Ocean (south of Ghana)
Scientific name for the Northern Lights		Aurora borealis
Scientific name for the Southern Lights		Aurora australis
Libyan city, where the highest ever temperature in the shade – 134°C – was recorded in 1922		El Aziza (Al Aziziyah)
Term coined in 1875 by the Austrian geologist Edward Suess, to refer to those parts of the Earth's surface that are able to support life; now defined (by Wikipedia) as "the sum of all ecosystems"		Biosphere
Enlarged shadow seen against cloud when the sun is low – named after the highest of the Harz Mountains in northern Germany where it is frequently seen		Brocken spectre (or bow)
Chalk and limestone consist essentially of (chemical compound)		Calcium carbonate
The process by which large chunks break away from glaciers and float off into the sea as icebergs or other ice debris		Calving
The highest type of cloud – name is from Latin for a lock of hair – colloquially known as "mare's tails"		Cirrus
Measured in oktas		Cloud cover
Lignite, bituminous and anthracite are the three types of		Coal
Rock fragment between 65mm and 256mm diameter (i.e. larger than a pebble but smaller than a boulder)		Cobble
The effect of the earth's rotation on winds, currents, and other objects on the surface; also a cause of the earth's magnetic field		Coriolis effect
Cloud type normally associated with thunderstorms – extending high into the atmosphere and producing a characteristic anvil shape when it reaches the tropopause		Cumulonimbus
An area of low atmospheric pressure; also the name used for a hurricane in the Indian and South Pacific oceans (cf. Typhoon)		Cyclone
The temperature to which air must be cooled to become saturated with water vapor, and below which the airborne water vapour will condense to form liquid water (dew); or (in technical terms), the temperature at which the water vapor in a sample of air at constant barometric pressure condenses into liquid water at the same rate at which it evaporates		Dew point
Early June to mid–August: the period when Sirius rises with the Sun, characterised by hot, stifling weather; known since Roman times as the		Dog Days
Name given by sailors to the belt of low pressure around the Equator – characterised by light winds and calms, but occasional sudden storms – caused by the meeting of trade winds		The Doldrums
Tectonic plate (see Sets) on which Great Britain is situated		Eurasian
Calm centre of a hurricane		Eye
Group of minerals said to make up 60% of the Earth's crust		Feldspars
Theory that the earth adapts itself in order to survive, in the same was as a living organism – formulated in the 1960s by the English independent research scientist James Lovelock, and named after the Greek supreme goddess of Earth		Gaia Hypothesis
Mica, feldspar, quartz: varieties of		Granite
The best–known result of thermohaline circulation		Gulf Stream (or North Atlantic Drift)
Campbell–Stokes Recorder measures		Hours of sunshine
Cold Northerly current on the Pacific coast of Chile and Peru		Humboldt Current
Amount of water vapour in the atmosphere		Humidity
Oceans, lakes, atmospheric water vapour, etc.: generic name		Hydrosphere
Milankovitch Hypothesis is concerned with		Ice age(s?)
Jack o'Lantern, Will o'the Wisp (mysterious lights that appear at dusk or twilight, especially over marshy or boggy ground): scientific name		Ignis fatuus
The plasma in the earth's atmosphere (mesosphere and thermosphere) which affects radio propagation and thus reflects radio waves back to earth		Ionosphere
The most abundant element in the planet Earth (34% by weight); makes up 80% of the core		Iron
Lines of equal pressure		Isobars
Lines of equal depth (of water)		Isobaths
Lines of equal sunshine hours		Isohels
Lines of equal rainfall		Isohyets
Lines of equal depth of cloud cover		Isonephs
Lines of equal temperature		Isotherms
Coldest month of the year in Britain		January
Warmest month of the year in Britain		July
High–velocity winds at altitudes of 30,000 to 50,000 feet (6 to 10 miles)		Jetstream
Layer in the ionosphere, altitude about 56 to 90 miles, that deflect radio waves and thus makes round–the–world transmissions possible; named after the US and British physicists who independently predicted its existence in 1902; detected 1924 by Sir Edward Appleton; now called the E region		Kennelly–Heaviside layer
Ribbon, rocket, streak and sheet are types of		Lightning
A fulgurite is an irregular, branching, often foamy hollow tube of silica glass, formed by the melting of quartz sand at very high temperatures, as a result of
The crust and the solid outermost layer of the mantle (down to approx 100km)		Lithosphere
Molten or semi–molten material, found beneath the surface of the Earth (and probably other planets), from which all igneous rocks are formed; produced by the melting of the mantle or the crust due to tectonic activity		Magma
The volume of space surrounding a planet, controlled by the planet's magnetic field		Magnetosphere
Semi–molten (plastic) layer between the outer core and the crust		Mantle
Boundary between the Mesosphere and the Thermosphere (altitude about 50 miles)		Mesopause
Tunguska, Siberia, 1908		Meteorite
Ambitious American attempt (1961) to drill through the Earth's crust into the Mohorovičić discontinuity, providing an Earth Science complement to the Space Race – from Guadalupe Island, off Baja California (Mexico – note: not Guadaloupe)		Project Mohole
The boundary between the crust and the mantle, marked by a rapid increase in the speed of earthquake waves		Mohorovičić (Moho) Discontinuity
Average length of one minute of arc on a great circle		Nautical mile
Tides with the least variation (highest low waters, lowest high waters) – occurring when the influences of the sun and moon are in opposition to one another		Neap
Second most abundant element in the earth's core (80% of which is iron)		Nickel
Rain cloud (from the Latin for a cloud or rainstorm)		Nimbostratus (f.k.a. nimbus)
Popular name for the Southern Oscillation, a warm Pacific current periodically (average once every 5 years) causing unpredictable worldwide weather conditions		El Niño (La Niña)
78% of the Earth's atmosphere is		Nitrogen
Amphidromic points (there are three in the North Sea)		No rise and fall in tides
Points on the Earth's surface where all lines of longitude meet		North and South Poles
Formed when a cold front overtakes a warm front; represented on a map by alternating semicircles (representing the warm front) and triangles (cold front)		Occluded front
Agulhas, Benguela, Canary, Humboldt and Kuroshio are examples of		Ocean currents
Abyssal, Bathyl, Hadal: zones of		Ocean depth
21% of Earth's atmosphere (most of the 22% that isn't nitrogen), and 49% of its crust, is		Oxygen
Second only to iron in the earth itself, by weight (28%)
The part of the stratosphere that absorbs ultra–violet rays; discovered in 1913 by the French physicists Charles Fabry and Henri Buisson		Ozone layer
Soil that's been below 0°C for two years or more		Permafrost
Nival zone (on a mountain)		Permanent snow cover
Rain, snow, hail etc.: generic name, to meteorologists		Precipitation
Term used in cartography for an attempt to reproduce the three–dimensional surface of the earth in two dimensions		Projection
You would find (in ascending order) an understory layer, a canopy layer and an emergent layer in a		Rainforest
Second most abundant material in the Earth's crust, after feldspar		Quartz
Hyet– (e.g. isohyet, hyetograph)		Rainfall
'Haboob' is a name (originating in Sudan) for a		Sand storm (or dust storm)
The word 'eustatic' refers to worldwide changes in		Sea level
Name given by geologists to the uppermost layer of the Earth's crust – derived from the names of its two main constituents (see next question)		Sial
The main constituent of the rock that forms the earth's mantle and crust (various compounds, of silicon, oxygen, one or more metals, and sometimes hydrogen)		Silicates
The second most abundant element in the Earth's crust (27% – oxygen 49%)		Silicon
Prevailing wind direction in the British Isles		South–west
Luminous electrical discharge from lightning conductors, ships' masts etc. in a thunderstorm		St. Elmo's Fire
Tectonics: the movement of one plate sliding under another		Subduction
The ocean or sea that was formed when Pangaea split to form Laurasia and Gondwanaland – named after the wife of the sea god Oceanus, in Greek mythology		Tethys (Sea or Ocean)
Imaginary lines linking the furthest points from the Equator where the Sun can be directly overhead (at midday)		Tropics
An exceptionally large wave, typically following an earthquake or a volcanic eruption on or below the ocean bed (from a Japanese word meaning 'harbour wave')		Tsunami
Boundary between the troposphere and the stratosphere – where temperature starts to increase with height, instead of decreasing		Tropopause
The name used for a hurricane in the North Pacific (cf. Cyclone)		Typhoon
Two belts of charged particles, held in place by the Earth's magnetic field, above the magnetosphere – confirmed in 1958 by the Explorer I and III space missions – named after the US space scientist who suggested that Geiger counters should be taken on those missions		Van Allen belts
Aphotic zone (lakes and oceans)		Very deep (no light)
The most abundant and most potent greenhouse gas in the Earth's atmosphere		Water vapour

© Haydn Thompson 2017–23