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MSCE Geography practice questions

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Question 1Physical Geography: Earth structure, rocks, weathering and landform processes

Which layer of the Earth is composed mainly of solid iron and nickel and lies beneath the liquid outer core?

  1. The asthenosphere
  2. The oceanic crust
  3. The lower mantle
  4. The inner core Correct answer.

Explanation

The inner core is the central zone of the Earth, and despite extreme temperatures it remains solid because of the enormous pressure above it. Its composition is dominated by iron with some nickel. The asthenosphere, mantle and crust all lie above the outer core.

Question 2Physical Geography: Earth structure, rocks, weathering and landform processes

The Mohorovičić discontinuity (Moho) marks the boundary between which two zones?

  1. The lower mantle and the outer core
  2. The crust and the mantle Correct answer.
  3. The outer core and the inner core
  4. The lithosphere and the asthenosphere

Explanation

The Moho is a seismic boundary identified by an abrupt increase in seismic wave velocity, and it separates the crust from the underlying mantle. It is not a compositional boundary within the core, nor the rheological boundary at the base of the lithosphere.

Question 3Physical Geography: Earth structure, rocks, weathering and landform processes

According to plate tectonic theory, new oceanic lithosphere is generated at which type of boundary?

  1. A transform boundary
  2. A divergent boundary at a mid-ocean ridge Correct answer.
  3. A convergent boundary at an ocean trench
  4. A passive continental margin

Explanation

At mid-ocean ridges, diverging convection-driven plates allow mantle material to rise, decompress and melt, producing basaltic magma that solidifies as new oceanic crust. This process, sea-floor spreading, adds lithosphere on both sides of the ridge axis.

Question 4Physical Geography: Earth structure, rocks, weathering and landform processes

Which rock type forms from the cooling and solidification of molten material?

  1. Metamorphic rock
  2. Sedimentary rock
  3. Bioclastic rock
  4. Igneous rock Correct answer.

Explanation

Igneous rocks crystallise from magma or lava as it cools, producing either intrusive rocks with coarse crystals or extrusive rocks with fine crystals. Sedimentary and metamorphic rocks form by other pathways entirely.

Question 5Physical Geography: Earth structure, rocks, weathering and landform processes

Which weathering process is primarily a chemical reaction in which minerals absorb water and expand, causing rock to flake?

  1. Frost shattering
  2. Salt crystallisation
  3. Hydrolysis Correct answer.
  4. Exfoliation by thermal stress

Explanation

Hydrolysis is a chemical weathering process in which water reacts with minerals such as feldspar, converting them into clay minerals and weakening the rock. It is distinct from purely mechanical processes like frost shattering and salt growth.

Question 6Physical Geography: Earth structure, rocks, weathering and landform processes

A river deposits a fan-shaped body of coarse sediment where it leaves a steep mountain valley and enters a flat plain. This landform is best described as which of the following?

  1. A meander
  2. A floodplain
  3. A delta
  4. An alluvial fan Correct answer.

Explanation

When a steep-gradient stream abruptly loses gradient, its competence falls and coarse sediment is deposited in a fan shape at the valley mouth. This landform is an alluvial fan. A delta forms where a river enters standing water such as a lake or sea.

Question 7Physical Geography: Earth structure, rocks, weathering and landform processes

Which term describes the proportion of a rock's volume made up of open spaces?

  1. Viscosity
  2. Permeability
  3. Competence
  4. Porosity Correct answer.

Explanation

Porosity is the volumetric proportion of void space in a rock or sediment. Permeability, by contrast, measures how readily fluid can flow through those connected spaces; a rock can be porous but impermeable.

Question 8Physical Geography: Earth structure, rocks, weathering and landform processes

Which of the following is a sedimentary rock formed chiefly from the calcium carbonate remains of marine organisms?

  1. Limestone Correct answer.
  2. Basalt
  3. Granite
  4. Slate

Explanation

Limestone is a sedimentary rock composed largely of calcium carbonate, often derived from accumulated shells and skeletons of marine organisms or by chemical precipitation. Granite and basalt are igneous, and slate is metamorphic.

Question 9Physical Geography: Earth structure, rocks, weathering and landform processes

Which seismic wave type is a compressional body wave that travels fastest and passes through both solids and fluids?

  1. Rayleigh waves
  2. Love waves
  3. P-waves Correct answer.
  4. S-waves

Explanation

P-waves are compressional waves in which particle motion is parallel to the direction of travel, and they are the fastest seismic waves. Because fluids resist compression, P-waves propagate through liquids as well as solids, unlike S-waves.

Question 10Physical Geography: Earth structure, rocks, weathering and landform processes

The discovery that S-waves do not pass through the Earth's outer core is used to infer which property of that layer?

  1. That it is rigid and crystalline
  2. That it is composed of silicate minerals
  3. That it is denser than the inner core
  4. That it behaves as a liquid Correct answer.

Explanation

S-waves are shear waves and cannot propagate through material that lacks shear strength, so their absence beyond the core shadow zone indicates that the outer core is liquid. This is one of the key seismic lines of evidence for a fluid outer core.

Question 11Physical Geography: Earth structure, rocks, weathering and landform processes

At a subduction zone, which feature is characteristically formed on the overriding plate?

  1. An abyssal plain
  2. A volcanic arc Correct answer.
  3. A mid-ocean ridge
  4. A transform fault parallel to the trench

Explanation

As the subducting slab descends, water released from it lowers the melting point of the overlying mantle wedge, generating magma that rises to form a volcanic arc on the overriding plate. Mid-ocean ridges and abyssal plains form at divergent settings instead.

Question 12Physical Geography: Earth structure, rocks, weathering and landform processes

A coarse-grained igneous rock with large crystals forms when magma does which of the following?

  1. Cools slowly at depth Correct answer.
  2. Cools rapidly at the surface
  3. Solidifies from a silica-poor lava flow
  4. Erupts explosively as ash

Explanation

Slow cooling at depth allows crystals time to grow large, producing a coarse-grained (phaneritic) intrusive texture. Rapid surface cooling produces fine-grained or glassy rocks because crystals have little time to develop.

Question 13Physical Geography: Earth structure, rocks, weathering and landform processes

Which metamorphic rock typically forms from the metamorphism of limestone?

  1. Quartzite
  2. Schist
  3. Gneiss
  4. Marble Correct answer.

Explanation

Limestone, composed largely of calcite, recrystallises under heat and pressure to form marble. Quartzite derives from quartz sandstone, and schist and gneiss form from a range of parent rocks under higher-grade conditions.

Question 14Physical Geography: Earth structure, rocks, weathering and landform processes

In a region of alternating wet and dry seasons, salt crystals grow within pores of porous rock and force grains apart. This is an example of which process?

  1. Mechanical weathering by salt crystallisation Correct answer.
  2. Chemical weathering by oxidation
  3. Mechanical weathering by frost shattering
  4. Chemical weathering by carbonation

Explanation

Salt crystallisation is a mechanical weathering process: as saline water evaporates, salt crystals grow and exert pressure that prises grains apart. No chemical change to the minerals is required for the rock to disintegrate.

Question 15Physical Geography: Earth structure, rocks, weathering and landform processes

Which combination of conditions most strongly promotes rapid chemical weathering of granite?

  1. Cold, wet climate with sparse vegetation
  2. Hot, dry climate with sparse vegetation
  3. Warm, wet climate with abundant vegetation Correct answer.
  4. Cold, dry climate with little vegetation

Explanation

Chemical weathering reactions are accelerated by high temperatures and abundant moisture, and vegetation contributes organic acids and roots that further promote breakdown. Warm, wet, vegetated environments therefore favour rapid chemical weathering.

Question 16Physical Geography: Earth structure, rocks, weathering and landform processes

A river's velocity decreases as it enters a lake. Which sediment size is deposited last, furthest from the river mouth?

  1. Clay Correct answer.
  2. Silt
  3. Gravel
  4. Coarse sand

Explanation

As current velocity falls, the largest and heaviest particles settle first and the finest last, a principle known as sorting by settling velocity. Clay particles remain suspended longest and are deposited furthest out, often in deeper water.

Question 17Physical Geography: Earth structure, rocks, weathering and landform processes

Which process is primarily responsible for the formation of a U-shaped valley?

  1. River deposition
  2. Glacial erosion Correct answer.
  3. Chemical weathering along joints
  4. Wind abrasion

Explanation

Glaciers erode their beds by abrasion and plucking, widening and deepening pre-existing valleys into a characteristic U-shaped cross-profile. Rivers tend to produce V-shaped valleys through incision, and wind and chemical weathering do not produce this form.

Question 18Physical Geography: Earth structure, rocks, weathering and landform processes

A limestone cave system contains stalactites hanging from the ceiling and stalagmites rising from the floor. Which process explains their growth?

  1. Abrasion by sediment-laden water
  2. Evaporation of saline groundwater
  3. Precipitation of calcium carbonate from dripping water Correct answer.
  4. Freeze-thaw shattering of the cave roof

Explanation

Water rich in dissolved calcium bicarbonate drips into the cave, loses carbon dioxide and precipitates calcium carbonate, building speleothems such as stalactites and stalagmites. This is a chemical deposition process, not mechanical erosion.

Question 19Physical Geography: Earth structure, rocks, weathering and landform processes

Which statement best explains why the asthenosphere permits lateral movement of tectonic plates?

  1. It is a rigid layer of cold lithosphere.
  2. It is a liquid layer of molten iron.
  3. It is a weak, partially molten layer that can flow slowly over geological time. Correct answer.
  4. It is a zone of high-pressure solid rock with no deformation.

Explanation

The asthenosphere is near its melting point and behaves plastically, deforming by slow creep that allows the rigid lithospheric plates above to move. It is not a fully molten metallic layer, nor is it rigid.

Question 20Physical Geography: Earth structure, rocks, weathering and landform processes

A sedimentary sequence shows coarse conglomerate overlain by sandstone, then shale, then limestone. Which interpretation is most consistent with these observations?

  1. A gradual increase in depositional energy over time
  2. A gradual decrease in depositional energy and increasing distance from the sediment source Correct answer.
  3. Repeated glacial advances over the same site
  4. A single catastrophic flood deposit with no sorting

Explanation

The upward fining from conglomerate to shale and limestone indicates progressively lower current energy and finer sediment reaching the site, typical of a transgression or retreat from the source. Coarser material settles where energy is highest and finer material further out.

Question 21Physical Geography: Earth structure, rocks, weathering and landform processes

Which type of plate boundary is associated with shallow-focus earthquakes but neither significant volcanism nor crustal creation or destruction?

  1. Transform boundary Correct answer.
  2. Ocean-ocean convergent boundary
  3. Continental collision zone
  4. Divergent boundary

Explanation

Transform boundaries accommodate horizontal sliding between plates, generating shallow earthquakes along the fault but little or no magma production and no net creation or destruction of lithosphere. Divergent and convergent boundaries involve crustal addition or loss.

Question 22Physical Geography: Earth structure, rocks, weathering and landform processes

A rock sample contains abundant olivine and pyroxene with little quartz. This composition indicates which origin?

  1. A chemically precipitated limestone
  2. A silica-poor mantle-derived magma Correct answer.
  3. A metamorphosed shale
  4. A silica-rich continental crust magma

Explanation

Olivine and pyroxene are mafic minerals rich in magnesium and iron and low in silica, characteristic of mantle-derived magmas such as basalt. Silica-rich magmas instead crystallise quartz and feldspar, and sedimentary or metamorphic origins do not fit this mineral assemblage.

Question 23Physical Geography: Earth structure, rocks, weathering and landform processes

In a soil profile developed on a humid temperate slope, which horizon is characterised by accumulation of illuviated clay and iron oxides?

  1. The C horizon
  2. The O horizon
  3. The B horizon Correct answer.
  4. The A horizon

Explanation

The B horizon is the zone of accumulation where materials leached from overlying horizons, such as clay, iron and aluminium oxides, are deposited. The O and A horizons are organic-rich surface layers subject to leaching, and the C horizon is weathered parent material.

Question 24Physical Geography: Earth structure, rocks, weathering and landform processes

Which reasoning best explains why a coastline formed of jointed limestone erodes faster than one formed of massive granite under the same wave climate?

  1. Granite contains more joint sets, which makes it more resistant
  2. Granite has a lower density and is therefore more easily transported by waves
  3. Limestone has a higher density and is therefore more easily undercut
  4. Limestone is more porous and permeable, so wave-induced compression and chemical solution exploit its joints Correct answer.

Explanation

Limestone's porosity and permeability allow water to enter joints, where air compression and chemical solution (carbonation) weaken the rock, so erosion proceeds faster. Granite is comparatively impermeable and resistant, and density differences do not control resistance in the way described.

Question 25Physical Geography: Earth structure, rocks, weathering and landform processes

A geologist observes pillow lavas, sheeted dykes and gabbro in an ophiolite sequence. Which setting does this assemblage indicate?

  1. A continental collision zone
  2. A karst cave system
  3. A mid-ocean ridge system Correct answer.
  4. A subduction trench

Explanation

Ophiolite sequences preserve oceanic lithosphere: pillow lavas erupted on the sea floor, sheeted dykes that fed them and gabbro crystallised beneath the ridge. This layered assemblage is diagnostic of a mid-ocean ridge setting later obducted onto a continent.

Question 26Physical Geography: Earth structure, rocks, weathering and landform processes

Which layer of the Earth is defined by its ability to flow plastically over geological time, allowing the rigid plates above to move independently?

  1. The asthenosphere Correct answer.
  2. The mesosphere
  3. The outer core
  4. The lithosphere

Explanation

The asthenosphere lies beneath the rigid lithosphere and is close to its melting point, so it deforms ductilely over long timescales and provides the weak zone on which plates slide. The lithosphere above it is rigid and broken into plates, so it cannot itself be the flowing layer.

Question 27Physical Geography: Earth structure, rocks, weathering and landform processes

A geologist classifies a specimen as an extrusive igneous rock. Which set of features would best support that classification?

  1. Fine-grained or glassy texture with possible vesicles Correct answer.
  2. Coarse interlocking crystals of quartz and feldspar
  3. Rounded pebbles cemented by finer sediment
  4. Parallel alignment of platy minerals

Explanation

Extrusive rocks solidify at or near the surface, where cooling is rapid, so crystals have little time to grow and the rock is fine-grained or glassy; trapped gas may leave vesicles. Coarse interlocking crystals indicate slow, intrusive cooling instead.

Question 28Physical Geography: Earth structure, rocks, weathering and landform processes

A slope of jointed sandstone in a humid region is undercut by a road cutting. Which combination of factors most directly raises the risk of a rockfall along the new cut face?

  1. Cementation of joints by secondary minerals combined with lower pore pressure
  2. Deeper weathering of the bedrock combined with a thicker soil cover
  3. Steepened slope angle combined with reduced basal support Correct answer.
  4. Increased vegetation cover combined with gentler slope angle

Explanation

Removing the toe of a slope increases its angle and removes the material that was buttressing the jointed rock, so shear stress on the joints rises and blocks can detach. Vegetation, cementation and pore-pressure reduction all tend to stabilise a face rather than promote failure.

Question 29Physical Geography: Earth structure, rocks, weathering and landform processes

In a glaciated upland, a ridge of unsorted, angular debris runs across a valley. Which interpretation of this landform is most consistent with its form and sediment?

  1. An alluvial fan built where a tributary leaves a gorge
  2. A terminal moraine marking a former ice limit Correct answer.
  3. A sand dune built by prevailing winds
  4. A point bar deposited on the inside of a meander

Explanation

Unsorted, angular debris in a ridge crossing a valley is typical till, and a transverse ridge marks where an advancing or retreating glacier paused, forming a terminal moraine. Fluvial and aeolian landforms would show rounded, sorted sediment and different shapes.

Question 30Physical Geography: Earth structure, rocks, weathering and landform processes

Two limestone outcrops have identical mineralogy and climate, but one is intensely jointed while the other is massive. Which reasoning best explains why the jointed outcrop dissolves and erodes faster?

  1. Joints lower the permeability of the rock, so water remains at the surface and attacks it longer
  2. Joints increase the surface area exposed to carbonated water and allow water to penetrate the rock mass Correct answer.
  3. Joints reduce the rock's calcium carbonate content, making each fragment chemically weaker
  4. Joints raise the proportion of insoluble quartz, which dissolves preferentially along the fractures

Explanation

Chemical weathering of limestone by carbonated water proceeds at the rock surface, so a dense joint network multiplies the exposed area and lets water circulate deep into the mass, widening fissures into karst conduits. The jointed rock therefore retreats faster than the massive outcrop of the same composition.

Question 31Weather, Climate and Atmosphere

Which atmospheric layer contains the ozone layer that absorbs most ultraviolet radiation?

  1. Thermosphere
  2. Stratosphere Correct answer.
  3. Troposphere
  4. Mesosphere

Explanation

The ozone layer is concentrated in the stratosphere, roughly 15-35 km above the surface, where ozone molecules absorb the bulk of incoming ultraviolet radiation. This absorption warms the stratosphere and creates the temperature inversion that stabilizes it.

Question 32Weather, Climate and Atmosphere

On a standard day at sea level, the average atmospheric pressure is closest to which value?

  1. 1500 hPa
  2. 500 hPa
  3. 1013 hPa Correct answer.
  4. 760 hPa

Explanation

Standard sea-level pressure is about 1013 hPa (1013 mb), equivalent to 29.92 inches of mercury. This value is the reference against which surface pressure readings are compared on synoptic charts.

Question 33Weather, Climate and Atmosphere

Which instrument measures relative humidity directly by comparing a wet-bulb and dry-bulb reading?

  1. Barometer
  2. Campbell-Stokes recorder
  3. Anemometer
  4. Sling psychrometer Correct answer.

Explanation

A psychrometer uses two thermometers, one kept wet; evaporation cools the wet bulb, and the temperature difference gives relative humidity via tables. The drier the air, the greater the depression of the wet bulb.

Question 34Weather, Climate and Atmosphere

Air flowing from the subtropical high toward the equator is deflected to the right in the Northern Hemisphere, forming which wind belt?

  1. Westerlies
  2. Doldrums
  3. Northeast trade winds Correct answer.
  4. Polar easterlies

Explanation

Equatorward flow from the subtropical high is deflected rightward by the Coriolis effect in the Northern Hemisphere, giving the northeast trade winds. Their southern-hemisphere counterparts blow from the southeast.

Question 35Weather, Climate and Atmosphere

What type of cloud is typically associated with stable air and appears as thin, layered sheets?

  1. Cumulus
  2. Altocumulus castellanus
  3. Cumulonimbus
  4. Stratus Correct answer.

Explanation

Stratus clouds form in stable, layered air with weak vertical motion, producing flat featureless sheets. They often bring drizzle or overcast conditions rather than showers.

Question 36Weather, Climate and Atmosphere

Which process transfers heat through the direct contact of air molecules without bulk movement of the air?

  1. Convection
  2. Advection
  3. Conduction Correct answer.
  4. Radiation

Explanation

Conduction transfers energy through molecular collisions when air is in direct contact with a warmer or cooler surface. It is most effective in the thin layer of air next to the ground.

Question 37Weather, Climate and Atmosphere

What is the primary cause of the seasonal variation in day length at a mid-latitude location?

  1. The precession of the equinoxes over 26,000 years
  2. Changes in the Sun's energy output
  3. The tilt of Earth's axis relative to its orbital plane Correct answer.
  4. Variations in Earth's orbital speed

Explanation

The 23.5-degree axial tilt means each hemisphere leans toward or away from the Sun through the year, changing both the angle of incidence and the length of the daylight arc. That tilt is the dominant control on seasonal day length.

Question 38Weather, Climate and Atmosphere

A parcel of air at 20 degrees C with a relative humidity of 50 percent is cooled. At approximately what temperature does it reach saturation?

  1. About 0 degrees C
  2. About 25 degrees C
  3. About 9 degrees C Correct answer.
  4. About 18 degrees C

Explanation

The dew point is the temperature to which air must be cooled at constant pressure to reach saturation. For 20 degrees C air at 50 percent relative humidity, the dew point is roughly 9 degrees C. Cooling below that value produces condensation.

Question 39Weather, Climate and Atmosphere

An air parcel at 15 degrees C is lifted dry adiabatically by 500 metres. If the dry adiabatic lapse rate is 10 degrees C per km, what is its new temperature?

  1. 15 degrees C
  2. 12.5 degrees C
  3. 10 degrees C Correct answer.
  4. 5 degrees C

Explanation

Lifting 500 m at 10 degrees C per km cools the parcel by 5 degrees C. Starting at 15 degrees C, the parcel reaches 10 degrees C, provided it stays unsaturated throughout.

Question 40Weather, Climate and Atmosphere

What weather condition should a forecaster expect immediately behind a fast-moving cold front?

  1. Persistent fog with calm winds
  2. A sharp temperature drop with clearing skies and gusty winds Correct answer.
  3. Long spells of gentle stratiform rain
  4. Steady warm drizzle with rising temperatures

Explanation

Cold fronts are steep and advance quickly, so the passage brings a rapid temperature fall, a wind veer and often a burst of heavy showers followed by clearing. The cold, dense air behind the front is typically drier and more stable.

Question 41Weather, Climate and Atmosphere

A station reports a wind of 250 degrees at 20 knots. Toward which compass direction is the wind blowing?

  1. Toward 160 degrees
  2. Toward 250 degrees
  3. Toward 70 degrees Correct answer.
  4. Toward 340 degrees

Explanation

Wind direction is reported as the direction from which the wind blows. A 250-degree wind comes from the west-southwest and therefore blows toward 70 degrees, the opposite bearing.

Question 42Weather, Climate and Atmosphere

Why do coastal locations typically have a smaller diurnal temperature range than inland locations at the same latitude?

  1. Land surfaces absorb more heat than water during the day
  2. Coastal locations receive less solar radiation
  3. Water has a higher specific heat capacity and mixes heat through a deeper layer Correct answer.
  4. Coastal air contains more ozone

Explanation

Water's high specific heat and its ability to mix heat downward mean the sea warms and cools slowly, moderating adjacent air temperatures. Land heats and cools rapidly, so continental interiors show much larger day-night swings.

Question 43Weather, Climate and Atmosphere

What does a steep environmental lapse rate in the lower troposphere indicate for rising air parcels?

  1. Stronger atmospheric stability
  2. Saturated air at all levels
  3. Greater potential instability Correct answer.
  4. A temperature inversion

Explanation

When the environmental lapse rate is steeper than the parcel's adiabatic rate, a lifted parcel stays warmer than its surroundings and keeps rising. That condition defines potential instability and favours convective cloud and showers.

Question 44Weather, Climate and Atmosphere

Which condition is required for radiation fog to form overnight over land?

  1. Clear skies, light winds and high near-surface humidity Correct answer.
  2. A rapidly deepening low-pressure centre
  3. Strong winds and heavy cloud cover
  4. A steep lapse rate with vigorous convection

Explanation

Radiation fog forms when the ground cools strongly under clear skies, chilling the adjacent moist air to its dew point. Light winds promote gentle mixing of the cooling layer without dispersing it; strong winds or cloud prevent the necessary cooling.

Question 45Weather, Climate and Atmosphere

What is the main reason the ITCZ shifts northward during the Northern Hemisphere summer?

  1. The subtropical highs intensify over the oceans
  2. The zone of maximum solar heating and convection migrates with the overhead Sun Correct answer.
  3. The Coriolis force weakens at the equator
  4. Trade winds reverse direction seasonally

Explanation

The ITCZ follows the belt of strongest surface heating, so it migrates toward the hemisphere experiencing summer. Its northward shift brings the wet season to regions such as the Sahel and northern India.

Question 46Weather, Climate and Atmosphere

In the mid-latitudes, what is the main energy source that drives the development of a frontal cyclone?

  1. Downward transport of heat from the stratosphere
  2. Baroclinic instability along the polar front Correct answer.
  3. Friction between air and the land surface
  4. Latent heat released by tropical thunderstorms

Explanation

Mid-latitude cyclones grow from baroclinic instability, in which strong horizontal temperature gradients along the polar front provide available potential energy. Upper-level divergence and the jet stream then steer and intensify the system.

Question 47Weather, Climate and Atmosphere

A weather station reports a dew point depression of 1 degree C and a temperature of 18 degrees C. What is the most likely near-surface condition?

  1. A pronounced temperature inversion aloft
  2. Strong convective showers
  3. Mist or shallow fog with high relative humidity Correct answer.
  4. Very dry air with excellent visibility

Explanation

A dew point depression of only 1 degree C means the air is very close to saturation, giving relative humidity near 95 percent. Under light winds this favours mist or shallow fog and reduced visibility.

Question 48Weather, Climate and Atmosphere

Why does the tropopause generally sit higher over the equator than over the poles?

  1. Stronger convective heating at the equator lifts the boundary of the troposphere Correct answer.
  2. The equator receives less cosmic radiation
  3. The Coriolis force is stronger at the equator
  4. Polar air is more humid and expands

Explanation

Intense solar heating and deep convection near the equator expand the troposphere, pushing the tropopause to roughly 16-18 km. At the poles, cold dense air and weak convection place it near 8-10 km.

Question 49Weather, Climate and Atmosphere

A sample of air at 20 degrees C holds 10.4 g of water vapour per kg of dry air. If saturation at 20 degrees C is about 14.9 g per kg, what is the relative humidity?

  1. About 90 percent
  2. About 50 percent
  3. About 30 percent
  4. About 70 percent Correct answer.

Explanation

Relative humidity is the actual vapour content divided by the saturation value, multiplied by 100. Dividing 10.4 by 14.9 gives roughly 0.70, or 70 percent.

Question 50Weather, Climate and Atmosphere

Which statement best explains why the subtropical highs are located near 30 degrees latitude rather than at the equator?

  1. Air aloft from the Hadley cell subsides around 30 degrees, creating high surface pressure Correct answer.
  2. Ocean currents warm the surface at 30 degrees
  3. The Coriolis force is strongest near 30 degrees
  4. Surface friction is greatest near 30 degrees

Explanation

Air rising at the ITCZ moves poleward aloft, cools radiatively and sinks near 30 degrees latitude, producing the subtropical high-pressure belts. Subsidence also suppresses cloud and creates many of the world's deserts.