Chapter 3: Solar Energy and Earth-Sun Relationships

Vocabulary flashcards covering key terms and concepts from the notes on the Sun–Earth system, planetary science, and solar energy basics.

Galaxy

A gravitationally bound collection of stars, gas, and dust; the Milky Way is one.

Milky Way

A spiral galaxy containing over 100 billion stars; our Sun is one of them.

Star

A glowing ball of gas held together by its own gravity and powered by nuclear fusion at its core.

Light-year

A distance unit equal to about 9.5 trillion kilometers (6 trillion miles); distance light travels in one year.

Solar system

All celestial bodies that orbit a star due to its mass and gravity; the Sun holds about 99.8% of the system’s mass; eight planets orbit the Sun.

Gravity

The attractive force between objects; stronger with more mass.

Sun

A medium-sized, self-luminous star that powers Earth’s climate through solar radiation; energy from nuclear fusion in its core.

Nuclear fusion

The process of fusing hydrogen into helium at a star’s core, releasing vast energy.

Solar wind

Outward flow of charged particles from the Sun’s corona; travels ~400 km/s and interacts with Earth’s magnetic field.

Planet

A body that orbits the Sun, is nearly spherical, and has cleared its orbital neighborhood.

Terrestrial planet

Rocky, metallic planets with solid surfaces (e.g., Mercury, Venus, Earth, Mars).

Gas giant

Large planets composed mainly of gases and ices with no solid surface (Jupiter, Saturn, Uranus, Neptune).

Pluto

A dwarf planet reclassified in 2006; likely originated in the Kuiper Belt; smaller than the Moon.

Rotation

Spinning of a planet on its axis; Earth completes one rotation roughly every 24 hours.

Revolution

Orbit of a planet around the Sun; Earth takes about one year to complete a revolution.

Axial tilt

Tilt of Earth’s axis relative to the plane of its orbit, about 23.5°, causing seasons.

Axial parallelism

Axis maintains a fixed orientation in space as the Earth orbits the Sun (north toward Polaris).

Sphericity

Earth’s shape is nearly spherical; it is an oblate spheroid illuminated by parallel Sun rays.

Ecliptic plane

The plane of Earth’s orbit around the Sun; reference plane for the zodiac.

Subsolar point

Point on Earth where the Sun is directly overhead and insolation is maximal.

Declination

Latitude where the Sun’s rays are directly overhead; varies through the year.

Tropic of Cancer

23.5° N latitude; northern boundary where the Sun can be overhead at noon.

Tropic of Capricorn

23.5° S latitude; southern boundary where the Sun can be overhead at noon.

Arctic Circle

66.5° N latitude; region with extreme day/night variations (polar day/night).

Antarctic Circle

66.5° S latitude; region with extreme day/night variations (polar day/night).

Solstice

Two annual events: Summer solstice (≈June 21) with Sun overhead at Tropic of Cancer; Winter solstice (≈Dec 21) overhead at Tropic of Capricorn.

Equinox

Two annual events: Vernal (≈March 20–21) and Autumnal (≈Sept 22–23) when Sun is overhead at the equator and day equals night.

Analemma

A figure-8 diagram showing the Sun’s declination and the longitude of the Sun over a year.

Insolation

Incoming solar radiation; energy reaching Earth’s atmosphere or surface, measured in W/m^2.

Shortwave radiation

Sun’s energy in ultraviolet, visible, and shortwave infrared wavelengths; higher energy.

Longwave radiation

Earth’s emitted thermal infrared radiation; longer wavelengths, lower energy.

Ultraviolet

Short-wavelength, high-energy radiation from the Sun (about 0.2–0.4 micrometers).

Visible light

Wavelengths roughly 0.4–0.7 micrometers; the portion of the spectrum visible to humans.

Infrared

Wavelengths longer than visible light; includes near to thermal infrared; associated with heat.

Electromagnetic spectrum

Range of all wavelengths of electromagnetic radiation from gamma rays to radio waves.

Earth’s energy budget

Balance between incoming solar radiation and outgoing Earth infrared radiation that determines climate.

why is geography known as a spatial discipline?

Geography is known as a spatial discipline because it studies the relationships between locations and the patterns of human and physical phenomena across the Earth's surface.

what are some topics in physical geography that illustrate THE ROLE OF GEOGRAPHY AS A SPATIAL SCIENCE?

landforms, climate patterns, ecosystems, and natural resources, all of which illustrate spatial relationships and processes.

how does the study of systems relate to the role of geography as a physical science?

The study of systems in geography examines how various physical and human processes interact and influence each other across different spatial scales, highlighting the interconnectedness of the Earth's systems.

how does a holistic approach mean in terms of thinking about an environmental problem?

considering the entire system, including social, economic, and ecological factors, rather than addressing isolated components. This perspective helps in understanding the complex interrelationships and impacts of various elements within the environment.

how do open and closed system differ?

Open systems exchange both matter and energy with their surroundings, while closed systems exchange only energy, not matter. This distinction is crucial for understanding environmental processes and system interactions.

Is Earth an open or closed system?

Earth is considered a closed system for matter, as it does not exchange significant amounts of matter with its surroundings, but it is an open system for energy, receiving solar energy from the sun and radiating energy back into space.

what specific advantages do computer and digital technologies offer to the mapmaking process? 

Computer and digital technologies enhance the mapmaking process by enabling rapid data collection and analysis, improving accuracy through advanced modeling, allowing for easy updates and modifications, and facilitating the integration of multimedia elements for richer visualization.

differences between a parallel and a meridian in terms of their orientation, geographic difference, and role in the coordinate system.

Parallels are lines of latitude that run east-west and are parallel to the equator, while meridians are lines of longitude that run north-south, converging at the poles. Together, they form the geographic coordinate system used for locating positions on the Earth's surface.

How does each help in determining location on earth

Parallels and meridians work together to create a grid system that allows for precise location determination on Earth, with parallels indicating latitude and meridians indicating longitude.

what time zone is the U.S in?

The U.S. spans multiple time zones, primarily including Eastern, Central, Mountain, and Pacific Time, each representing one hour of difference from the others.

what is the time difference between Greenwich Mean Time and your time zone.

The time difference between Greenwich Mean Time (GMT) and your time zone varies depending on your location, typically ranging from UTC-12 to UTC+14, reflecting hours ahead or behind GMT.

what does the concept of thematic map layers mean in geographic information systems

Thematic map layers in geographic information systems (GIS) refer to the various data sets that can be overlaid on a map to represent different types of information, such as population density, land use, or climate zones, allowing for in-depth spatial analysis and visualization.

how does earth’s rotation and revolution affect insolation and influence life on earth.

Earth's rotation and revolution influence insolation by determining the amount and angle of sunlight received at different locations, which affects climate patterns, seasonal changes, and the distribution of life on Earth.

compare shortwave radiation and longwave radiation in terms of their sources, wavelengths, and roles in Earth energy balance.

Shortwave radiation is primarily emitted by the sun, with wavelengths ranging from 0.1 to 4 micrometers, while longwave radiation is emitted by the Earth, typically ranging from 4 to 100 micrometers. Both types of radiation play crucial roles in the Earth's energy balance, with shortwave radiation providing energy for heating the Earth and longwave radiation being essential for cooling.

how does each type of radiation interact with the atmosphere and earth surface.

Shortwave radiation interacts with the atmosphere by being scattered and absorbed, while longwave radiation is emitted by the Earth's surface and can be absorbed and re-emitted by greenhouse gases in the atmosphere, affecting temperature and climate.

Explain the key differences between solstices and equinoxes in terms of Earths position relative to the sun. 

Solstices occur when the Earth's axis is tilted the most towards or away from the sun, resulting in the longest and shortest days of the year, while equinoxes occur when day and night are nearly equal in length as the sun is directly above the equator.

what are the 2 major factors that cause regular variations in insolation throughout the year? How do they cause season?

The two major factors are the tilt of the Earth's axis and its elliptical orbit around the sun. These factors cause variations in insolation by changing the angle and duration of sunlight received at different latitudes, leading to the changing seasons.