Physical Geography Exam 2

Tropical Cyclones

intense, low-pressure storm systems that form over warm tropical oceans, characterized by strong rotating winds, heavy rain, and a central calm eye.

Hydroclimate

The study of water in the atmosphere and its interactions with the land surface

latent heat

Heat released or absorbed during a change of state

Sea Surface Temperature (SST)

is the temperature of the ocean’s surface layer, which influences weather patterns, ocean currents, and the development of storms like tropical cyclones.

Coriolis Force

force caused by the Earth’s rotation, which deflects moving objects to the right in the northern hemisphere and to the left in the southern hemisphere

Easterly Waves

low-pressure waves in the trade wind belt that move east to west, causing convergence on the east side (rising air and storms) and divergence on the west side (sinking air and clear skies). 

Convergence

The coming together of air at lower levels which leads to rising air. Leads to cloud formation and storms

Divergence

The spreading out of air at higher levels which helps to draw air upwards from the surface (air spreading apart in the upper troposphere), helps storms intensify because rising air is evacuated efficiently at high attitudes. 

warm water, unstable air, moisture, low wind shear, Coriolis force, pre-existing disturbance (easterly wave)

6 main formation factors:

Role of Warm Water 

Warm ocean water provides latent heat through evaporation; this energy drives convection and strengthens the storm. 

Eye

calm, low-pressure center where air descends due to centripetal balance. 

Eye Wall

ring of intense convection surrounding the eye, strongest winds and heaviest rainfall

Self-Sustaining Process of Cyclones

Rising moist air releases latent heat, which lowers surface pressure, draws in more air, and maintains the storm’s intensity

Geographic Locations of Cyclones

Typically form in tropical oceans between 5-20 degrees latitude, not along the equator; regions include the Atlantic, Pacific, and Indian Oceans. 

Why Cyclones Weaken Over Land

Loss of warm water energy source, increased friction, and reduced moisture supply weaken the system. 

Cyclogenesis

The formation of a midlatitude cyclone along a stationary front where cold and warm air masses meet. 

Open Stage

Distinct warm and cold fronts develop; counterclockwise rotation (in NH) begins to intensify, characteristic comma shaped ‘opening’ in the cyclone

Occluded Stage

The cold front overtakes the warm front, lifting warm air aloft and cutting off the storm’s energy source

Midlatitude Cyclones

a large low-pressure storm that forms where warm and cold air masses meet, producing rotating winds and changing weather conditions in the midlatitudes. 

Polar Front Theory

explains that midlatitude cyclones form along the boundary (polar front)between cold polar air and warm tropical air, where temperature contrasts cause rising motion and storm development. 

Conveyor Belt Model

describes the movement of warm, cold, and dry air streams within a midlatitude cyclone, showing how these interacting airflows create clouds, precipitation, and the storm’s overall structure. 

Air Masses

are large bodies of air with uniform temperature and moisture characteristics that form over specific source regions and influence the weather of the areas they move over. 

Open Stage

is the phase of a midlatitude cyclone when distinct warm and cold fronts develop, and the storm intensifies as warm air rises between advancing cold and retreating warm air.

Occluded Stage 

occurs when the cold front overtakes the warm front, lifting the warm air off the ground and cutting off the cyclone’s energy source, leading to its weakening. 

Prevailing Winds

are the consistent, dominant wind patterns in a region that result from global atmospheric circulation and the uneven heating of Earth’s surface. 

Dissolving Stage

is the final phase of a midlatitude cyclone when the storm weakens and dissipates as temperature differences between air masses decrease and energy is lost. 

Cold Front

is the boundary where a cold air mass advances and pushes under a warmer air mass, often causing clouds, precipitation, and a drop in temperature. 

Warm Front

is the boundary where a warm air mass advances over a colder air mass, typically bringing gradual cloud formation and steady, prolonged precipitation. 

Role of the Jet Stream

provides upper-level divergence that supports rising air and surface low pressure, connecting upper and surface systems.

Vorticity

is the measure of the rotation of air in the atmosphere, indicating how much and how quickly an air parcel spins around a vertical axis

Identifying Fronts to a Map

Cold front (blue triangles), warm front (red semicircles), occluded front (purple line with both symbols).

Meeting of Air Masses

Cyclones form where cold, dry polar air meets warm, moist tropical air, creating instability.

Upper-level divergence

refers to the pattern of atmospheric features, such as winds, pressure, and temperature, in the upper levels of the atmosphere that influence surface weather systems and storm development. 

Earth’s Water Distribution

~97% saltwater, ~3% freshwater; most freshwater is frozen, and only ~1% is accessible surface water

Surface vs. Subsurface Water

Surface includes rivers, lakes, streams; subsurface includes soil moisture and groundwater.

Atmosphere Component of Hydrologic Cycle

Involves evaporation, transpiration, and condensation of water vapor.

Surface Water Component

Includes lakes, rivers, and runoff pathways transporting water across land.

Warm Conveyor Belt

is a stream of warm, moist air in a midlatitude cylclone that rises ahead of the cold front, producing clouds and precipitation as it moves poleward and upward. 

Cold Conveyor Belt

is a stream of cool, moist air that flows westward and beneath the warm front in a midlatitude cyclone, then rises and turns poleward around the storm’s center, contributing to cloud and precipitation formation. 

Dry Conveyor Belt

is a stream of cool, dry air that descends from the upper troposphere behind a cold front in a midlatitude cyclone, often clearing skies and creating dry, stable conditions. 

Water Budget

is the balance between the inputs (like precipitation) and outputs (like evaporation and transpiration) of water in a system, showing whether there is a surplus or deficit. 

Subsurface Water Component

refers to water found below Earth’s surface, including soil moisture and groundwater stored in pores and rock layers. 

Groundwater Structure

refers to the arrangement of underground water zones, including the unsaturated zone (aeration) above and the saturated zone below, where all pores are filled with water.

Aquifer Types

confined aquifer has an impermeable layer above; unconfirmed aquifer has direct surface recharge. 

Vadose Zone/Zone of Aeration

is the layer between the land surface and the water table where soil pores contain both air and water but are not fully saturated. 

Zone of Saturation/Phreatic Zone

is the subsurface layer where all soil and rock pores are completely filed with water. 

Recharge Process

is the movement of water from the surface into the ground to replenish aquifer or the zone of saturation

Cone of Depression

is the downward, cone-shaped lowering of the water table around a well caused by groundwater being pumped out faster than it can be replenished. 

Unconfined Aquifer

is a groundwater storage area that has a permeable layer on top and is directly recharged by surface water infiltrating through the soil. 

Confined Aquifer

is a groundwater storage area trapped between two impermeable layers, so its water is under pressure and typically recharged only in distinct locations where the confining layer is absent. 

Aquifer

is a body of permeable rock or sediment that stores and transmits groundwater, allowing it be extracted for use. 

Aquiclude

is a layer of impermeable rock or sediment that does not allow water to pass through, effectively blocking groundwater flow.

Water Budget Concepts

compares input (precipitation) and output (evaporation + transpiration); surplus = wet conditions, deficit = dry conditions. 

Saltwater Intrusion

is the movement of seawater into freshwater aquifers, usually near coastal areas, often caused by excessive ground water pumping. 

Evapotranspiration

the combined process of water evaporating from soil and water surfaces and being released by plants through transpiration. 

Actual Evapotranspiration (AET)

the amount of water that is actually removed from a surface through the combined processes of evaporation and transpiration under existing moisture conditions. 

Potential Evapotranspiration (PET)

the amount of water that would be evaporated and transpired by plants if there were unlimited water available. 

Evaporation

the process by which liquid water changes into water vapor and enters the atmosphere

Transpiration

the process by which water is absorbed by plant roots, moves through the plant, and is released as water vapor from leaves into the atmosphere. 

Porosity vs. Permeability

the percentage of a rock or sediment’s volume that consists of open spaces or pores that can store water, while permeability is the ability of a rock or sediment to allow water to flow through those pores. 

Gravitational Water

water that fills the pore space of soil and then gets pulled down by gravity (saturation)

Permeability

the ability of a rock, soil, or sediment to allow water or other fluids to pass through its pores. 

Capillary Water

water that is held to soil particles by capillary action (Field Capacity)

Hygroscopic Water

water that is held to soil particles by capillary action, but beyond what can be accessed by plant roots (wilting point)

Field Capacity

The maximum capacity of soil to hold water

Wilting Point

the point where all water available is hygroscopic and unavailable to plants (i.e. plants begin to wilt)

Ocean Geography

Major basins include Pacific, Atlantic, Indian, Arctic, and Southern Oceans. 

Properties of Seawater

Salinity (~35%), temperature, and density determine seawater characteristics. 

Sounding 

Place a weight on a string and let it fall

Echo Soundings

Send a ping to the ocean floor and wait for a reflection

Seabeam

Multiple echo soundings in various directions

Satellites

measure the surface ocean and infer the ocean floor

Temperature Structure

Warm surface layer, thermocline (rapid temperature change), and cold deep layer.

Thermocline

Region of rapid temperature change with depth

Salinity Patterns

Higher near subtropics (evaporation); lower near equator or poles (precipitation, ice melt)

Halocline

Region of rapid salinity change with depth

Brine Rejection

Formation of sea ice excludes salt forming brine

Density Patterns

Higher density from cold, salty water; lower from warm, fresh water.

Ocean Nutrients and Upwelling

Nutrients concentrated in deep waters; upwelling brings them to the surface, supporting marine life. 

Wind Stress

Force of wind on the ocean surface initiating current movement.

Ekman Spiral

Current direction shifts with depth due to Coriolis effect, surface water move 45 degrees to wind, deeper layers rotate further.

Shear Stress

Is the force per unit area exerted by wind moving across the ocean surface, which causes the water to start moving and generates ocean currents. 

Ekman Transport

the net movement of a column of water at about 90 degrees to the direction of the prevailing wind, caused by the combined effects of wind stress, the Coriolis effect, and the Ekman spiral.

Ekman Pumping and Suction

the vertical movement of ocean water caused by the convergence (pumping, downward) or divergence (function, upward) of surface currents driven by wind and the Coriolis effect. 

Upwelling

upward movement of cold, nutrient-rich water from deeper layers of the ocean to the surface, often caused by diverging surface currents.

Downwelling

the downward movement of surface water toward deeper layers of the ocean, usually occurring where surface currents converge, transporting oxygen-rich water to depth. 

Gyre

a large, circular system of ocean currents formed by global wind patterns, the Coriolis effect. and the configuration of continents. 

five major gyres

North & South Atlantic, North & South Pacific, and Indian Ocean.

Western Boundary Currents

fast, deep, warm ocean currents found on the western edges of ocean basins, transporting heat from the tropics toward higher latitudes (e.g., Gulf Stream, Kuroshio Current).

Climate Impacts of Western Currents

Western boundary currents transport warm water from the tropics toward higher latitudes, moderating coastal climates by raising temperatures and influencing precipitation patterns.

Antarctic Circumpolar Current

a strong, continuous ocean current that flows eastward around Antarctica, connecting the Atlantic, Pacific, and Indian Oceans and driving global ocean circulation.

Indian Ocean Circulation

the pattern of surface currents in the Indian Ocean, which reverses seasonally due to monsoon winds, affecting regional climate and ocean conditions.

Peruvian Upwelling

the rising of cold, nutrient-rich deep water to the surface along the coast of Peru, driven by winds and the Coriolis effect, supporting high marine productivity.

Walker Circulation

is an east–west atmospheric circulation over the equatorial Pacific, where warm air rises over the western Pacific, flows eastward aloft, sinks over the cooler eastern Pacific, and returns at the surface, driving trade winds and influencing El Niño and La Niña events.

Buoyancy

the upward force exerted on an object or water parcel that is less dense than the surrounding fluid, allowing it to float or rise.

Thermohaline Circulation

the global ocean circulation driven by differences in water density, which are controlled by temperature (thermo) and salinity (haline), moving heat and nutrients around the world’s oceans.

Deep Water Formation Regions

areas in the ocean, such as the North Atlantic, Weddell Sea,and Ross Sea, where surface water becomes very dense due to cooling and increased salinity, causing it to sink and drive thermohaline circulation.

Global Conveyor Belt

a continuous, worldwide system of surface and deep ocean currents that redistributes heat, salt, and nutrients, linking all the oceans and regulating Earth’s climate.

Circulation Timescale

the approximate time it takes for a parcel of water to complete a full loop of the global thermohaline (ocean) circulation, typically around 1,500–2,000 years.

Thermohaline Circulation and Climate Change

how rising global temperatures and melting ice can alter ocean temperature and salinity, potentially slowing or disrupting the deep-ocean currents that regulate global climate.