Weather Dynamics: Global Geography, Atmospheric Circulation, Ocean Currents, and Extreme Weather

Vocabulary practice flashcards covering global geography, atmospheric pressure systems, air masses, front types, global wind belts, ocean currents, and extreme weather phenomena from Science 1206 Unit 1 Section 1.2.

Longitude

The angle measured east or west from the $0^\circ$ line (the prime meridian), represented by vertical lines that run north to south, with the International Date Line located at approximately $180^\circ$ longitude.

Latitude

The angle measured north or south of the $0^\circ$ line (the equator), represented by horizontal lines that run east to west.

Tropic of Cancer

A major reference line of latitude in the Northern Hemisphere located at $23.5^\circ\text{ N}$.

Arctic Circle

A reference line of latitude in the Northern Hemisphere located at $66.5^\circ\text{ N}$.

Tropic of Capricorn

A major reference line of latitude in the Southern Hemisphere located at $23.5^\circ\text{ S}$.

Antarctic Circle

A reference line of latitude in the Southern Hemisphere located at $66.5^\circ\text{ S}$.

Tropics

The large equatorial region located between the Tropic of Cancer and the Tropic of Capricorn that receives the most direct heat from the sun.

Polar Regions

The geographic regions located north of the Arctic Circle and south of the Antarctic Circle that receive the least amount of direct sunlight.

Mid-latitudes

The region located between the tropics and the polar regions that receives a moderate amount of direct sunlight and encompasses most of Canada.

Earth's Axial Tilt

The $23.5^\circ$ tilt of Earth on its axis, which, along with the curvature and revolution of Earth around the sun, causes the changing seasons.

Weather System

A set of temperature, wind, pressure, and moisture conditions for a certain region that moves as a unit over a period of days.

Air Mass

A very large mass of air that takes on the temperature and moisture properties of the surface over which it forms when resting fairly still for days or weeks.

Arctic Air Mass

An air mass that forms over the Arctic, characterized by bitter, cold, dry conditions in winter and cold, dry conditions in summer, which moves in a southeasterly direction across North America.

Continental Polar ($\text{cP}$) Air Mass

An air mass that forms over mainland Canada, characterized by very cold and dry air in winter and cold, dry air in summer, typically moving south toward the southeast.

Continental Tropical ($\text{cT}$) Air Mass

An air mass forming over the southern United States and Mexico, characterized by warm, dry air in winter and hot, dry air in summer, moving northward.

Maritime Polar ($\text{mP}$) Air Mass

An air mass forming over Alaska in the Pacific Ocean and over Labrador and Greenland in the Atlantic Ocean, characterized by cold and humid conditions in both winter and summer, moving southerly.

Maritime Tropical ($\text{mT}$) Air Mass

An air mass that forms over tropical regions of the Pacific Ocean, Atlantic Ocean, Caribbean, and Gulf of Mexico, bringing warm and humid air in winter and hot, humid air in summer while moving northward.

High-Pressure System

A weather system that forms when an air mass cools over an ocean or cold land, causing the air to become denser, sink, and circulate clockwise in the Northern Hemisphere, typically bringing clear skies.

Low-Pressure System

A weather system that develops when air warms, expands, and rises over warm land or ocean surfaces, circulating counterclockwise in the Northern Hemisphere and causing water vapour to condense into clouds and precipitation.

Front

A boundary zone that develops as a result of the meeting of two air masses with different characteristics, frequently producing clouds, precipitation, and changes in weather.

Cold Front

A front where advancing cold, dense air displaces warm air by pushing under it along a steep slope, forcing the warm air upward to cool and condense, producing thunderstorms or heavy rain/snow.

Warm Front

A front where advancing warm air displaces cold air by sliding up and over it along a gradual boundary slope, bringing gentle rain or light snow followed by warmer, milder weather.

Stationary Front

A stalled boundary occurring when two air masses with small temperature and pressure differences meet, but neither has the force to displace the other, resulting in many days of cloudy conditions and precipitation.

Occluded Front

A boundary formed when a fast-moving cold air mass overtakes a warm front, lifting the warm air mass entirely off the ground between two cold air masses and producing strong winds and heavy precipitation.

Wind

The horizontal movement of air from an area of higher air pressure to an area of lower air pressure.

Coriolis Effect

An inertial force caused by Earth's rotation that deflects moving air and water to the right in the Northern Hemisphere and to the left in the Southern Hemisphere, with deflection increasing as wind speed increases.

Air Pressure Gradient

The difference between regions of high and low air pressure that shifts air toward lowest pressure; a greater difference creates a stronger gradient and higher wind speeds.

Prevailing Winds

Winds that blow predominantly from a single general direction over a particular point on Earth's surface, generated by a combination of global convection currents and the Coriolis effect.

Trade Winds

Global wind systems occurring between the equator and $30^\circ$ latitude, formed as warm air rises at the equator, cools and sinks at $30^\circ$, and flows back toward the equator, deflecting right to create northeast trade winds in the north and left to create southeast trade winds in the south.

Polar Easterlies

Global wind systems occurring between $60^\circ$ latitude and the poles, formed as air rises at $60^\circ$, falls at the high-pressure poles, and flows back southward, deflecting to the right in the Northern Hemisphere.

Prevailing Westerlies (Mid-latitude Westerlies)

Global prevailing wind systems occurring between $30^\circ$ and $60^\circ$ latitude, formed by air moving from high pressure at $30^\circ$ toward low pressure at $60^\circ$, deflected to the right in the Northern Hemisphere.

Sea Breeze (Water Breeze)

A local daytime wind caused by land heating faster than water, which makes air over the land rise while cooler, denser air from above the water moves onshore to replace it.

Land Breeze

A local nighttime wind caused by land cooling faster than water, which makes warmer air over the water rise while cooler air from above the land moves offshore to replace it.

Jet Streams

Narrow bands of fast-moving westerly wind in the upper atmosphere caused by large temperature gradients combined with the Coriolis effect, separating colder air to the north from warmer air to the south.

Polar Jet Stream

The major jet stream located between $40^\circ$ and $60^\circ$ latitude that separates the polar easterlies from the prevailing westerlies.

Subtropical Jet Stream

The minor jet stream located between $20^\circ$ and $30^\circ$ latitude that separates the trade winds from the prevailing westerlies.

Ocean Currents

The movement of water within the oceans that transfers thermal energy from equatorial regions to polar regions, categorized into surface currents and deep ocean currents.

Surface Currents

Horizontal ocean movements in the upper ocean influenced by winds, continents, and the Coriolis effect, circulating clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere.

Deep Ocean Currents

Vertical and horizontal ocean movements driven by differences in water temperature and salinity, where cold, high-salinity water sinks and displaces warmer water.

Thermohaline Circulation

The vertical movement of deep ocean currents driven by differences in heat ('thermo') and salt content ('haline').

Great Ocean Conveyor Belt

A massive worldwide interconnected system of deep-water and surface currents that redistributes thermal energy around the entire planet.

Labrador Current

A cold, low-salinity surface current flowing south along the coast of Newfoundland and Labrador that produces a pronounced summer cooling and moderating effect on coastal regions.

Gulf Stream

A warm surface current flowing northward that carries thermal energy and humid air to Newfoundland and Labrador, resulting in milder winter temperatures than those found in inland Canada.

Grand Banks Fog

A dense, frequent fog created where the cold, dry air above the Labrador Current interacts with the warm, moist air of the Gulf Stream, making the Grand Banks one of the foggiest places on Earth.

Thunderstorm

A storm featuring lightning, thunder, heavy rain, and sometimes hail, formed when water vapour in rising air rapidly condenses and releases thermal energy in unstable atmospheric conditions, creating thunderheads at the top of the troposphere.

Tornado

A violently rotating funnel of air and moisture that forms in severe thunderstorms when strong horizontal winds tilt rapidly rising air, turning right due to the Coriolis effect and traveling at speeds up to $100\text{ km/h}$.

Broadside Flood

A seasonal, predictable type of flood that covers a large geographic land area, such as monsoon flooding.

Flash Flood

A flood characterized by a sudden, rapid onset that is difficult to predict, exemplified by the flooding event in Badger, Newfoundland and Labrador.

Drought

An extended period of abnormally low precipitation, common in high-pressure descending air belts at or near $30^\circ$ latitude, such as the 1930s Dust Bowl in the prairies.

Cyclones (Hurricanes, Typhoons, Tropical Cyclones)

Massive, high-energy low-pressure systems fueled by warm marine air spinning off equatorial oceans, called hurricanes in the Atlantic Ocean, typhoons in the Pacific Ocean, and tropical cyclones in the Indian Ocean.

Blizzard

A severe winter storm with low temperatures and winds exceeding $55\text{ km/h}$, formed when a warm, moisture-laden air mass moves north and collides with a cold Arctic air mass under a strong jet stream.

Heat Wave

A period of more than $3$ consecutive days with temperatures at or above $32^\circ\text{C}$, often caused by high-pressure systems from southern continental air masses and intensified by temperature inversions over urban areas.

Humidex Scale

A numerical scale combining ambient air temperature and relative humidity to indicate perceived temperature to humans.

Wind Chill Factor

An index that takes into account the cooling effect of wind on exposed skin to determine how cold ambient temperatures feel.

El Niño

A seasonal climatic disruption resulting from high surface water temperatures and elevated water levels in the western Pacific, shifting Pacific convection currents and often leading to warmer temperatures in Canada.

La Niña

A climatic phenomenon caused by abnormally low surface water temperatures in the eastern Pacific, altering ocean convection currents and often resulting in colder temperatures in Canada.

Nor'easter

A powerful cyclonic storm bringing high winds, heavy precipitation, flooding, and surging waves, formed when cold, dry air carried by the jet stream meets warm, moist air from the Gulf of Mexico region.

Antarctic Circumpolar Current

An ocean current that flows uninterrupted around Antarctica without being deflected away by a continental landmass.