Atmosphere and weather

Question 1

Absorption of energy

Answer 1

The process whereby incoming and outgoing radiation is absorbed by gases in the atmosphere such as ozone water vapour and carbon dioxide, as well as by the land and oceans

Question 2

Advection fog

Answer 2

Condensation of atmospheric vapour at low levels due to cooling of relatively warm, moist air by contact with a cold surface. Local examples include Seafret of north east England and Haar of south east Scotland. Both are caused by warm continental air being chilled to its dew point temperature by contact with the cold North Sea

Question 3

Aerosols

Answer 3

Solid particles of dust, pollution etc which act as condensation nuclei

Question 4

Air mass

Answer 4

A large body of air with relatively uniform the temperature and humidity characteristics, generally characterised as polar or tropical, maritime or continental

Question 5

Albedo

Answer 5

The fraction of incoming radiation reflected by a given surface

Question 6

Anticyclone

Answer 6

A slow moving area of relatively high atmospheric pressure covering thousands of kilometres squared, often referred to as simply as high. Usually these pressure systems give clear skies and cold weather

Question 7

Cloud

Answer 7

A visible mass of microscopic water droplets and or ice crystals held in suspension by air currents, they are formed by condensation of water vapour around condensation nuclei such as smoke pollen dust salt

Question 8

Cold front

Answer 8

A long thin band of clouds and precipitation making the boundary between an advancing cold air mass and a retreating warm air mass

Question 9

Condensation

Answer 9

Process by which water vapour turns into water droplets when the temperature falls to dew point and the air become saturated with moisture

Question 10

Condensation level

Answer 10

The altitude at which rising air has been cooled to its dew point and water vapour has begun to condense into tiny cloud droplets

Question 11

Condensation nuclei

Answer 11

The process by which heat energy is transferred directly from a warmer to cooler substance, by molecular movement, e.g. from a warm ground surface to cooler air above

Question 12

Conduction

Answer 12

The process by which heat energy is transferred directly from a warmer to cooler substance by molecular movement

Question 13

Convection

Answer 13

The vertical transfer of heat energy by rising air currents warm land or sea surface heat the air above it, the air becomes less dense and rises up through the atmosphere, carrying heat energy with it

Question 14

Convectional precipitation

Answer 14

Caused by air rising above its condensation level to produce large cumulus clouds, usually occurs when relatively cool moist air is heated as it passes over relatively warm land or sea

Question 15

Coriolis effect

Answer 15

The deflection caused to moving air as it moves across the face of the rotating Earth, in the northern hemisphere is deflected to the right causing air to rotate anticlockwise around Lows and clockwise around highs

Question 16

Cumulus

Answer 16

Bubbly cauliflower clouds generated by relatively warm, moist air, they may be small, Fairweather cumulus or very large tall cumulonimbus clouds which generate heavy showers

Question 17

Depression

Answer 17

A low-pressure system developed on the polar front in the mid-latitude marked by a warm and cold front and warm sector. Often simply called a low

Question 18

Dew

Answer 18

Condensation at ground level, which usually occurs at night on that clear skies and light or, Calm winds, allowing plenty of heat loss

Question 19

Dew point

Answer 19

The temperature at which air become saturated with moisture and condensation begin to take place

Question 20

Drizzle

Answer 20

Drops of liquid precipitation less than 0.02 mm in diameter often associated with warm sectors of mid latitude Lows

Question 21

Environmental lapse rate

Answer 21

The rate at which the temperature of the atmosphere changes with height, measured in degrees Celsius per 100 m altitude. The temperature normally decreases at about 0. 6°C per 100 m, except when there is a temperature inversion, do not confuse this with the rate of temperature change experienced by a parcel of air

Question 22

Evaporation

Answer 22

The process by which liquid water transformed to gaseous water vapour

Question 23

Fog

Answer 23

Condensation of water vapour into cloud droplets at ground level, subdivided into radiation fog caused by overnight heat loss and advection fog, caused by warm moist air passing over a cold surface

Question 24

Freezing fog

Answer 24

Fog in the form of tiny crystals suspended in the air which sometimes occurs when the air temperature falls below 0°C

Question 25

Front

Answer 25

a band of clouds and precipitation occurs along the line of convergence of two air masses, one warm and one cold

Question 26

frontal ppt

Answer 26

rain, snow etc. which occurs along a front as warm air is forced to rise over cold air, or cold air undercuts warm air.

Question 27

frost

Answer 27

occurs when temperatures fall below 0oC; air frost occurs when the air (Stevenson screen) temperature falls below 0oC; ground frost when surface temperature is <0oC.

Question 28

general circulation

Answer 28

the global pattern of atmospheric movement.

Question 29

greenhouse effect

Answer 29

the warming of the atmosphere by the trapping of long-wave terrestrial re-radiation by certain gases such as CO2, water vapour and various pollutants.

Question 30

Hadley cell

Answer 30

the circulation of the atmosphere between the tropics of Cancer and Capricorn. Hot, moist air rises in the equatorial low, diverges towards higher latitudes, and then descends in the lower mid-latitudes to form the sub-tropical highs, returning to the equator as the Trade Winds.

Question 31

heat island

Answer 31

a zone of slightly higher temperatures associated with an urban area compared with surrounding rural areas. It can be caused by the absorption and storage of solar radiation by building materials as well as by the heat generated by traffic, industry and domestic heating systems.

Question 32

horizontal heat transfers

Answer 32

the transfer of heat across the globe by ocean currents, and by weather systems as both sensible and latent heat.

Question 33

hygroscopic nuclei

Answer 33

small particles in the air which attract water vapour which condenses to form cloud droplets; includes volcanic and desert dust, pollen, salt particles and many pollutants. Also called condensation nuclei.

Question 34

insolation

Answer 34

the incoming energy of the sun (heat, light, ultra-violet rays etc.)

Question 35

itcz

Answer 35

the zone of rising air and associated low pressure broadly coincident with the equator.

Question 36

latent heat

Answer 36

heat in a “hidden form” which changes the nature of a surface. Latent heat is absorbed (used) by water as it turns into vapour (evaporation), or when ice melts; it is released when condensation and freezing occur.

Question 37

long wave earth radiation

Answer 37

the long-wave heat energy given off by the earth back to space. Atmospheric gases such as water vapour and Carbon Dioxide absorb much of this radiation, causing the greenhouse effect.

Question 38

net radiation

Answer 38

the difference between incoming insolation and outgoing terrestrial re-radiation; an important determinant of temperature.

Question 39

North Atlantic drift

Answer 39

the relatively warm ocean current flowing northeastwards across the Atlantic Ocean, as an extension of the Gulf Stream, from the region around Florida towards Britain and Norway.

Question 40

ocean currents

Answer 40

large-scale circulations of ocean water carrying large quantities of heat from lower to higher latitudes, e.g. the North Atlantic Drift and the returning cold currents, e.g. the Canaries Current, taking the water back for re-heating.

Question 41

orographic ppt

Answer 41

rain, snow etc. generated by the forced uplift of moist air over mountains.

Question 42

ozone layer

Answer 42

a layer approximately between 15km and 55km above the earth’s surface where O3 is concentrated sufficiently to absorb significant amounts of ultra-violet radiation.

Question 43

polar cell

Answer 43

circulation of the atmosphere in the vertical and horizontal planes around the poles; air flows towards the poles at high altitudes, descends to the surface at the poles and flows away, as cold winds, from the poles at the surface.

Question 44

polar continental

Answer 44

air mass originating from northern Europe, Scandinavia and Siberia. Very cold and dry at source, but it picks up heat and moisture over the North sea and becomes unstable in its lower layers, generating cumulus clouds and snow showers.

Question 45

polar front

Answer 45

the junction between cold polar and warm tropical air along which depressions are generated.

Question 46

ppt

Answer 46

all forms of liquid drops and solid ice particles falling from clouds; includes rain, drizzle, sleet, snow, hail, mizzle, snizzle and fog-drip

Question 47

pressure gradient force

Answer 47

the difference in pressure (in millibars) per unit distance (in 100 km) between two places; the steeper the pressure gradient the stronger the wind.

Question 48

radiation

Answer 48

the transfer of energy (including heat and light) by electromagnetic waves of different wavelengths. Radiation is able to pass through gases, liquids, and solids or through a vacuum.

Question 49

solar radiation

Answer 49

the transfer of energy (including heat and light) by electromagnetic waves of different wavelengths. Radiation is able to pass through gases, liquids, and solids or through a vacuum.

Question 50

radiation fog

Answer 50

condensation (ground level cloud) generated by overnight heat loss; commonest on clear, calm winter nights when most radiation is lost from the ground.

Question 51

rain

Answer 51

drops of water of 0.02mm to 5mm diameter falling from clouds.

Question 52

rain shadow

Answer 52

an area on the sheltered side of a mountain range which receives less precipitation than on the windward side. Most of the precipitation falls as the moist air is forced to rise over the mountains (orographic precipitation), leaving the air drier as it descends again.

Question 53

reflection

Answer 53

the amount of radiation which bounces off an object. See albedo.

Question 54

relative humidity

Answer 54

the amount of water vapour in the air expressed as a percentage of the maximum amount could be held at the same temperature.

Question 55

scattering

Answer 55

process whereby insolation is scattered in all directions by dust and gases in the atmosphere, some reaching the earth’s surface as diffuse radiation.

Question 56

sensible heat

Answer 56

literally heat which can be felt – i.e. the heat of a substance as measured by its temperature; warm and cold air masses transporting heat energy between higher and lower latitudes.

Question 57

sleet

Answer 57

either partially melted, wet snow, or a mixture of rain and snow falling together.

Question 58

snow

Answer 58

large agglomerations of ice crystals falling from clouds.

Question 59

stratosphere

Answer 59

the next atmospheric layer above the troposphere, c.10 – 50km altitude.

Question 60

stratus clouds

Answer 60

layered clouds, classified according to their altitude; cirrostratus = highest, altostratus = middle, nimbostratus = lowest etc.

Question 61

sthp

Answer 61

region of high pressure found between latitudes 200 and 300 North & South, where the air in the Hadley Cell reaches the surface.

Question 62

temperature inversion

Answer 62

an increase in temperature with altitude, rather than the normal decrease. It can be caused by overnight cooling of the ground surface, warm air passing over a cold surface, or cold denser air sinking to ground level leaving warmer air above.

Question 63

terrestrial radiation

Answer 63

long-wave heat radiation given off by the earth/ oceans/ atmosphere back to space.

Question 64

trade winds

Answer 64

tropical winds blowing from the subtropical high to the equatorial low (ITCZ); NE Trades in northern hemisphere; SE Trades in southern hemisphere.

Question 65

tropopause

Answer 65

the imaginary boundary between the top of the troposphere and the bottom of the stratosphere; marked by a temperature inversion and acting as a vertical limit to cloud development.

Question 66

troposphere

Answer 66

the lower atmosphere in which all normal weather phenomena occur; from the surface up to the tropopause which varies between 18km altitude at the equator to 8km at the poles, depending on temperature, season etc.

Question 67

vertical heat transfers

Answer 67

transfer of heat up through the atmosphere by radiation, conduction and convection.

Question 68

warm fronts

Answer 68

band along which warm air rises up and over colder air, producing cloud and precipitation; usually stratus clouds and relatively light rain and drizzle.