Grade 10 Geography: Climatology, Geomorphology, Water Resources, and Population

Vocabulary practice flashcards covering atmospheric structures, weather systems, geology, plate tectonics, weathering, water resource management, and population geography from the Grade 10 notebook.

Troposphere

The lowest layer of the atmosphere (0–12 km) containing 75–80% of its total mass, where all weather occurs and temperature decreases with altitude at an average rate of $6.5\,^{\circ}\text{C/km}$.

Stratosphere

The atmospheric layer extending from 12 km to 50 km that contains ozone ($\text{O}_3$), lacks clouds, and acts as a temperature inversion layer where temperatures increase with height up to $0\,^{\circ}\text{C}$ at the stratopause.

Ozone Layer

A protective gaseous layer in the stratosphere composed of triatomic oxygen ($\text{O}_3$) that absorbs and filters out harmful solar ultraviolet (UV) radiation.

Mesosphere

The atmospheric layer extending from 50 km to 80 km where temperatures decrease with height to a minimum of approximately $-90\,^{\circ}\text{C}$ and where most meteors burn up upon entering the atmosphere.

Thermosphere

The uppermost atmospheric layer extending above 80 km, characterized by extremely thin air that absorbs energetic solar radiation, causing temperatures to rise to around $1\,200\,^{\circ}\text{C}$.

Insolation

Incoming short-wave solar radiation that passes through the atmosphere to heat the Earth's surface directly rather than heating the air directly.

Terrestrial Radiation

Long-wave heat energy emitted and re-radiated into the atmosphere and space by the Earth's surface after being heated by solar insolation.

Albedo

The measurement of the reflective property of a surface, defined as the proportion of incident solar radiation reflected rather than absorbed (e.g., snow possesses a high albedo, whereas dark soil has a low albedo).

Greenhouse Effect

The natural warming mechanism whereby atmospheric gases such as water vapour, carbon dioxide, and methane absorb and re-radiate outgoing terrestrial long-wave heat, maintaining Earth's surface roughly $33\,^{\circ}\text{C}$ warmer than it would otherwise be.

Chlorofluorocarbons (CFCs)

Synthetic chemical compounds containing carbon, chlorine, and fluorine used historically as aerosol propellants, refrigerants, and solvents that break down in the stratosphere and catalyse the destruction of ozone molecules.

Montreal Protocol

An international environmental treaty signed in Canada in 1987 designed to protect the Earth's ozone layer by mandating nations to phase out the production and use of ozone-depleting substances, including CFCs.

Lapse Rate

The rate at which atmospheric temperature decreases with an increase in altitude, averaging an environmental rate of $6.5\,^{\circ}\text{C}$ per $1\,000\,\text{m}$.

Temperature Inversion

An atmospheric condition in which temperature increases with altitude, frequently occurring in valleys on calm, clear winter nights when cold, dense air sinks to the valley floor and displaces warmer air upward.

Thermal Belt

A zone of warmer air trapped aloft on the mid-slopes of a valley between cold air sinking to the valley floor and cooler air in the upper atmosphere during a temperature inversion.

Maritime Climate

A coastal climate characterized by moderate temperatures with small diurnal and annual temperature ranges due to the moderating influence and high specific heat of the adjacent ocean.

Continental Climate

The climate of inland continental interiors characterized by large daily and seasonal temperature extremes because land surfaces warm and cool rapidly.

Aspect

The compass orientation of a slope relative to the sun; in the Southern Hemisphere, north-facing slopes receive direct sunlight and are warmer and drier, whereas south-facing slopes remain shaded and moister.

Dew Point

The critical temperature to which a parcel of air must cool at constant pressure in order to become completely saturated with water vapour, initiating condensation.

Relative Humidity

The ratio of the actual amount of water vapour present in a given mass of air compared to the maximum amount of water vapour the air could hold at that specific temperature, expressed as a percentage.

Cirrus

High-altitude (6–12 km), thin, feather-like, wispy clouds composed exclusively of ice crystals that frequently indicate an approaching cold front.

Cumulonimbus

A large, vertically towering rain cloud extending from 1–3 km up to the tropopause with an anvil-shaped top, capable of generating severe thunderstorms, lightning, heavy precipitation, and hail.

Orographic (Relief) Rain

Precipitation produced when moist air is forced upward over a mountain barrier, cooling adiabatically to its dew point to form clouds and rain on the windward side, leaving a dry rain shadow on the leeward side.

Cyclonic (Frontal) Rain

Rainfall that develops when two distinct air masses of contrasting temperatures meet, forcing lighter, warm air to rise over denser, colder air along a frontal surface.

Anticyclone

A high-pressure cell containing sinking, stable air that produces clear skies and dry conditions, circulating outward in an anti-clockwise direction in the Southern Hemisphere.

Cyclone

A low-pressure weather system containing rising, unstable air that causes cloud formation and rainfall, circulating inward in a clockwise direction in the Southern Hemisphere.

Isobar

A line plotted on a synoptic weather chart connecting places that experience equal atmospheric pressure, typically drawn at intervals of $4\,\text{hPa}$.

Cold Front

The leading boundary of an advancing cold air mass that undercuts and forces warm, moist air upward, leading to rapid cloud development, temperature drops of $5\,^{\circ}\text{C}$ or more, gusty winds, and precipitation.

Weather Station Model

A standardized symbolic notation on a synoptic weather chart that summarizes local meteorological data including temperature, dew point, cloud cover in oktas, wind speed, wind direction, and present weather.

Sial

The upper layer of the Earth's continental crust composed predominantly of silica and aluminium, consisting mainly of granitic rock with an average density of $2.8\,\text{g/cm}^3$.

Sima

The continuous lower layer of the Earth's crust that underlies continents and forms ocean basins, composed of silica and magnesium in basaltic rocks with an average density of $3.0\,\text{g/cm}^3$.

Asthenosphere

The partially molten, semi-plastic zone in the upper mantle situated directly beneath the lithosphere upon which tectonic plates float and move via convection currents.

Extrusive (Volcanic) Igneous Rock

Igneous rock formed when molten magma erupts onto the surface as lava and cools rapidly, resulting in fine-grained or glassy textures with small or microscopic crystals, such as basalt and obsidian.

Intrusive (Plutonic) Igneous Rock

Igneous rock formed when magma cools and solidifies slowly deep within the Earth's crust, permitting large, visible mineral crystals to develop, such as granite.

Intrusive Igneous Landforms

Subsurface magma structures including laccoliths (1), dykes (2), batholiths (3), volcanic pipes (4), sills (5), magma chambers (6), and lopoliths (7).

Batholith

A huge, deep-seated plutonic igneous intrusion of immense volume and undetermined depth that forms the core of many mountain ranges.

Dyke

A discordant sheet-like intrusion of igneous rock that cuts vertically or at a steep angle across existing bedding planes and strata.

Sill

A concordant, flat, horizontal sheet of igneous rock intruded parallel between existing bedding planes of sedimentary rock layers.

Laccolith

A dome-shaped or mushroom-shaped igneous intrusion with a flat floor that arches the overlying sedimentary rock strata upward under immense magma pressure.

Lopolith

A large, saucer-shaped igneous intrusion with a central depression that causes underlying sedimentary strata to sag downward under the weight of magma.

Sedimentary Rock

Rock formed by the weathering, erosion, deposition, compaction, and cementation of mineral particles (clastic), organic debris (organic), or chemical precipitates (chemical) in distinct strata.

Metamorphic Rock

Rock produced when pre-existing igneous or sedimentary rock undergoes recrystallization and mineral transformation as a result of intense heat, extreme pressure, or both.

Types of Folds

Geological wave structures resulting from compressive crustal stress, categorized as Open/Symmetrical (A), Asymmetrical (B), Overturned (C), Recumbent (D), or Isoclinal (E).

Anticline

An up-arched, convex fold in rock strata where the oldest rock layers lie at the core, typically forming topographic ridges.

Syncline

A down-arched, concave fold in rock strata where the youngest rock layers lie at the core, typically forming topographic troughs or valleys.

Overthrust Fold

A severely compressed fold where the pressure exceeds rock elasticity, snapping the axis along a thrust plane and forcing one rock limb over the other.

Normal Fault

A fault resulting from crustal extension (tensile stress) where the hanging wall moves downward relative to the footwall.

Reverse Fault

A fault resulting from crustal compression where the hanging wall is pushed upward relative to the footwall.

Horst and Graben

Crustal block landforms produced by extensional faulting where elevated fault blocks (horsts) stand adjacent to down-dropped valley blocks (grabens).

Rift Valley

A steep-sided, linear lowland formed on a divergent plate boundary where a central crustal block drops between parallel normal faults (e.g., the East African Rift).

Focus

The exact point deep within the Earth's crust where seismic rupture initiates and earthquake energy is released.

Epicentre

The point on the surface of the Earth located directly and perpendicularly above the subterranean focus of an earthquake.

Primary (P) Waves

Compressional seismic body waves that travel fastest through both solid rock and fluids, alternatingly compressing and dilating ground material along the direction of wave travel.

Secondary (S) Waves

Shear seismic body waves that move slower than P waves, vibrating particles perpendicular to wave travel and unable to propagate through liquids or molten outer core material.

Richter Scale

A base-10 logarithmic scale measuring earthquake magnitude based on the amplitude of the largest seismic waves recorded on a seismograph.

Moment Magnitude Scale ($M_w$)

A logarithmic measurement of total earthquake energy release calculated by multiplying the fault rupture area, average slip distance, and rock rigidity.

Tsunami

A series of ocean waves possessing immense wavelength and speed generated by sudden seabed displacement from subsea earthquakes, volcanic eruptions, or marine landslides.

Shield Volcano

A wide, broad-based volcano with gentle slopes ($5\text{--}10^{\circ}$) constructed from successive sheets of fluid, non-viscous basaltic lava erupted non-explosively (e.g., Mauna Loa in Hawaii).

Ash and Cinder Volcano

A steep-sided ($20\text{--}25^{\circ}$), cone-shaped volcano formed by violent explosive eruptions of pyroclastic rock fragments, cinders, and ash around a central vent (e.g., Parícutin in Mexico).

Composite Volcano (Stratovolcano)

A tall, steep-sided ($30\text{--}35^{\circ}$) volcano composed of alternating layers of hardened lava and pyroclastic ash emitted during explosive eruptions (e.g., Mount Fujiyama).

Caldera

A massive circular volcanic crater or basin created when the summit of a volcano collapses into an emptied underlying magma chamber following a catastrophic eruption.

Exfoliation

A mechanical weathering process in arid areas where severe diurnal temperature fluctuations cause outer rock layers to repeatedly expand and contract, fracturing and peeling off in concentric sheets.

Frost Shattering (Freeze-Thaw)

A mechanical weathering process occurring in cold climates where water enters rock crevices, freezes, and expands by roughly 9%, exerting stress that splits the rock apart.

Scree (Talus)

An accumulation of loose, angular rock fragments that gathers at the foot of a cliff or steep mountain slope as a result of mechanical weathering.

Carbonation

A chemical weathering process where carbonic acid formed from rainwater and atmospheric carbon dioxide dissolves calcium carbonate in limestone rock.

Clints and Grykes

Limestone pavement features where grykes are the widened solution fissures/joints and clints are the isolated, rectangular limestone blocks between them.

Mass Wasting

The downslope transfer of rock, regolith, and soil material under the direct pull of gravity without the aid of a transporting medium like running water or glacial ice.

500 mm Isohyet

The geographical rainfall boundary line dividing South Africa into a water-scarce western half and a water-sufficient eastern half.

Groundwater

Subsurface water that infiltrates the soil and percolates downward into underlying rock formations, accessed primarily through boreholes.

Population Geography

The scientific study of the spatial distribution, composition, migration patterns, and growth of human populations in relation to their environment.

Demography

The statistical study of human population parameters, including size, spatial structure, development, fertility, and mortality rates.

Population Distribution Patterns

Spatial settlement configurations classified as dispersed (spread across a territory), clustered (grouped closely together), or linear (arranged along a line).

Arithmetic (Crude) Population Density

The total number of people living in an area divided by the total land surface area, expressed as individuals per square kilometre ($\text{people/km}^2$).

Nutritional Population Density

The total population divided by the total area of cultivated (arable) land, reflecting the demographic pressure placed on agricultural food production.

Birth Rate (BR)

The total number of live births occurring within a given region per year per $1\,000$ people of the total population.

Death Rate (DR)

The total number of deaths occurring within a given region per year per $1\,000$ people of the total population.

Natural Increase Rate (NIR)

The percentage rate of annual population change calculated as the difference between the birth rate and the death rate, excluding net migration.

Fertility Rate

The average number of children a woman is projected to give birth to throughout her reproductive years in a given population.

Population Pyramid

A graphical representation illustrating the age-sex structure of a country's population, displaying males on the left, females on the right, and age cohorts vertically.

Demographic Transition Model (DTM)

A demographic model tracking the historical transition of birth and death rates over time across five distinct stages of socioeconomic modernization.

Brain Drain

The substantial loss of educated, highly skilled professionals (such as doctors and engineers) who emigrate from their home country to work in more developed nations.

Rural Depopulation

The decline in the population of rural communities caused by the sustained migration of working-age individuals to urban centers in search of employment and education.