Lecture Notes: Geography, Maps, Atmosphere—Key Terms (Vocabulary)

A comprehensive set of vocabulary flashcards covering latitude/longitude, map types and projections, Earth-Sun relations, atmosphere layers, weather/climate concepts, and basic meteorological processes.

Latitude

An angular distance north or south of the equator; lines run east–west and are called parallels.

Longitude

An angular distance east or west of the Prime Meridian; lines (meridians) run north–south and converge at the poles.

Equator

0° latitude line that divides the Earth into Northern and Southern Hemispheres; the longest circle of latitude.

Prime Meridian

0° longitude line that serves as the reference for measuring east–west locations.

Tropic of Cancer

23.5° N; boundary where the sun can be directly overhead at solar noon during part of the year.

Tropic of Capricorn

23.5° S; boundary where the sun can be directly overhead at solar noon during part of the year.

Northern Hemisphere

The half of the Earth north of the equator; latitude values are positive.

Southern Hemisphere

The half of the Earth south of the equator; latitude values are negative.

Eastern Hemisphere

The half of the Earth east of the Prime Meridian; longitudes are positive.

Western Hemisphere

The half of the Earth west of the Prime Meridian; longitudes are negative.

Rotation

The Earth’s spin on its axis, west to east; one rotation (day) is 24 hours.

Time Zone

A region where standard local time is the same; roughly 15° of longitude per hour.

15 Degrees Per Hour

The longitudinal width corresponding to one hour of time difference.

Hemisphere Sign Conventions

Latitude positive in the north, negative in the south; longitude positive east, negative west.

Great Circle

A circle on the globe whose center is the Earth’s center; e.g., the Equator and meridians.

Small Circle

Circles on the globe that do not pass through the Earth’s center; e.g., Tropics and Polar Circles.

Solstice

Times when the Sun reaches its maximum or minimum declination, causing longest or shortest day.

Equinox

Times when day and night are approximately equal in length.

Analemma

The figure-eight path of the Sun’s position in the sky over a year.

Declination

Latitude at which the Sun is directly overhead on a given date.

AOI (Angle of Incidence)

Angle between the Sun’s rays and a surface; determines solar intensity.

Zenith Angle

Angle between the vertical and the Sun; 0° when the Sun is overhead.

Aphelion

Point in Earth's orbit farthest from the Sun (around July 4).

Perihelion

Point in Earth's orbit closest to the Sun (around January 3).

Isobar

Line on a map connecting points of equal atmospheric pressure.

Isotherm

Line on a map connecting points of equal temperature.

Isoline

General term for lines that connect equal values (isobars, isotherms, etc.).

Graduated Circle

Map symbol where circle size represents data magnitude (e.g., population).

Choropleth

Thematic map shading areas according to data values.

Dot Map

Thematic map using dots to indicate occurrences or quantities.

Cylindrical Projection

Map projection good for global maps with less distortion near the equator; often used for world maps.

Conic Projection

Map projection using a cone to reduce distortion at mid-latitudes.

Geostationary Orbit

Satellite orbit at ~35,786 km above the equator; appears stationary from Earth.

Polar Orbit

Orbit that passes over the poles for global coverage; typical altitude ~500 miles.

UAS (Unmanned Aerial System)

Drone system including the aircraft and its supporting components.

GPS Space Component

The network of satellites in space that provide positioning signals.

GPS User Component

The receivers and software that compute position from satellite signals.

GPS Control Component

Ground control infrastructure that monitors and manages GPS satellites.

Remote Sensing

Acquiring information about the Earth's surface without direct contact, via sensors.

Aerial Photography

Photographs captured from aircraft for mapping and analysis.

Vertical Photograph

A photo taken with the camera pointed straight down (nadir view).

Oblique Photograph

An aerial photo taken at an angle, showing perspective.

Platform

The vehicle or platform from which imagery is captured (crane, UAS, aircraft, satellite).

GIS Layers (Geology, Population, Transportation, Forest Cover)

Data layers used in GIS to analyze spatial relationships (Geology, Population, Transportation, Forest Cover).

Uniform Gases

Gases with relatively constant mixing ratios in the atmosphere (O2 ~21%, N2 ~78%, Argon ~1%).

Oxygen

A uniform atmospheric gas comprising about 21% by volume.

Nitrogen

The most abundant atmospheric gas, about 78% by volume.

Argon

A noble gas present about 1% of the atmosphere.

Water Vapor

A variable gas (roughly 3–4% of the atmosphere) that strongly influences climate.

Carbon Dioxide

A greenhouse gas present about 0.036% of the atmosphere; contributes to the greenhouse effect.

Greenhouse Effect

Process by which greenhouse gases trap heat, warming the surface.

Homosphere

Lower, well-mixed portion of the atmosphere.

Heterosphere

Upper portion of the atmosphere where gases separate by molecular weight.

Ozone Layer

Region in the stratosphere with high concentrations of ozone that absorbs UV radiation.

Ozone

O3 molecule; essential for absorbing harmful UV radiation.

Troposphere

Lowest atmospheric layer; weather occurs here; temperature generally decreases with height.

Stratosphere

Layer above the troposphere; temp rises with height and contains the ozone layer.

Mesosphere

Layer above the stratosphere where temperatures typically decrease with height.

Thermosphere

Outer atmospheric layer where temperature rises with height; contains auroras.

Exosphere

Outermost atmospheric layer gradually transitioning into space.

Ionosphere

Layer with a high concentration of ions; affects radio wave propagation.

Weather Elements

Fundamental factors of weather and climate: temperature, humidity, pressure, wind, cloudiness, precipitation.

Temperature

Measure of the average kinetic energy of air molecules.

Humidity

Amount of water vapor in the air.

Pressure

Atmospheric force per unit area exerted by the air.

Wind

Movement of air from high to low pressure.

Cloudiness

Presence and amount of clouds in the sky.

Precipitation

Any form of water released to the Earth (rain, snow, sleet, hail).

Dew Point

Temperature at which air becomes saturated and condensation begins.

Relative Humidity

Percent of water vapor in the air relative to the maximum possible at the current temperature.

Absolute Humidity

Mass of water vapor per unit volume of air.

Specific Humidity

Mass of water vapor per unit mass of moist air.

Mixing Ratio

Mass of water vapor per unit mass of dry air.

Latent Heat

Heat absorbed or released during phase changes without a temperature change.

Sensible Heat

Heat that causes a change in temperature of a substance.

Evaporation

Liquid water turning into vapor, absorbing latent heat and cooling surfaces.

Condensation

Water vapor turning into liquid, releasing latent heat.

Sublimation

Solid to gas phase change; absorbs latent heat.

Deposition

Gas to solid phase change; releases latent heat.

Adiabatic Process

Temperature change due to vertical movement of air without heat exchange with surroundings.

Dry Adiabatic Lapse Rate

Rate at which rising dry air cools as it expands (about 9.8°C per km).

Wet Adiabatic Lapse Rate

Rate at which rising moist air cools, slower than dry due to latent heat release.

Albedo

Reflectivity of a surface; higher albedo means more solar reflection.

Mirage

Optical illusion from refraction of light in layers of air with different temperatures.

Pyranometer

Instrument used to measure solar irradiance (incoming solar radiation).

Dew Point vs Saturation

Dew point is where air becomes saturated; condensation occurs if cooled further.

Inversion

Layer where temperature increases with height, inhibiting vertical mixing.

Subsidence Inversion

Inversion formed by adiabatic heating of descending air at higher altitudes.

Surface Inversion

Inversion formed by radiational cooling of the ground at the surface.