Chapter 2 Solar Energy and the Seasons - Vocabulary Flashcards

Key terms and definitions covering the solar system, solar energy, space weather, and the seasons as presented in the lecture notes.

Nebula

A slowly rotating and collapsing cloud of dust and gas from which stars and planetary systems form.

Accretion

The process by which particles stick together and clump into larger bodies, leading to planet formation.

Proto-Sun

The dense, hot core that forms in a collapsing nebula and eventually becomes the Sun via nuclear fusion.

Sun

The star at the center of our solar system; composed mainly of hydrogen and helium, powered by nuclear fusion, with a magnetic field.

Hydrogen Fusion

Nuclear reaction where hydrogen atoms fuse to form helium, releasing energy in the process.

Sunspots

Dark, cooler regions on the Sun’s surface caused by magnetic activity; more sunspots increase solar radiation and follow an ~11-year cycle.

Solar Flare

A brief, intense eruption of energy and magnetic activity from the Sun’s surface.

Solar Wind

A continuous flow of electrically charged particles emitted from the Sun’s outer atmosphere (corona).

Magnetosphere

Earth’s protective magnetic field generated by movement in the outer core that shields the planet from radiation.

Aurora Borealis

Glow and light displays caused by interactions between the solar wind and Earth’s atmosphere.

Electromagnetic Spectrum

All wavelengths of electromagnetic radiation, from radio to gamma rays; the Sun emits primarily shortwave energy and Earth emits longwave energy.

Shortwave Radiation

High-energy electromagnetic radiation emitted by the Sun (ultraviolet, visible, near-infrared).

Longwave Radiation

Thermal infrared radiation emitted by the Earth back toward space.

Insolation

The incident solar radiation reaching Earth.

Subsolar Point

The location on Earth where the Sun is directly overhead; moves between 23.5°N and 23.5°S over the year.

Tropics

The regions between the Tropic of Cancer (23.5°N) and the Tropic of Capricorn (23.5°S) where sunlight can be overhead.

Declination

The latitude where the Sun is directly overhead on a given day; angle between the equator and the line to the Sun.

Altitude

The angle of the Sun above the horizon.

Vacant due to notes?

Placeholder term not used.

Seasons

Seasonal variations in sun’s position, daylength, and insulation due to Earth’s geometry and orbit.

Five Reasons for Seasons

Revolution, Rotation, Tilt of the axis, Axial parallelism, and Sphericity.

Revolution

Earth’s orbit around the Sun taking ~1 year (365.2422 days).

Rotation

Earth’s spin on its axis occurring each 24 hours; equatorial speed ~1674 km/h.

Obliquity (Tilt)

Tilt of Earth’s axis relative to its orbital plane, about 23.4°.

Axial Parallelism

The axis remains pointed in the same direction toward the North Star as Earth orbits the Sun.

Sphericity/Oblate Spheroid

Earth’s shape is an oblate spheroid, flatter at the poles and bulging at the equator.

Inner Planets (Terrestrial)

Small, dense, rocky planets (e.g., Mercury, Venus, Earth, Mars).

Outer Planets (Jovian)

Large, low-density gas/ice giant planets (e.g., Jupiter, Saturn, Uranus, Neptune).

Pluto (demotion)

Pluto is no longer classified as a planet (2006); it must orbit the Sun, be spherical, and clear its orbit.

Earth’s Energy Budget

Balance of energy: Sun’s shortwave radiation into Earth (input) and Earth’s longwave radiation back to space (output).