Terrestrial Planets and Atmospheres Flashcards

Vocabulary flashcards covering terrestrial planet interiors, internal heat sources, cooling mechanisms, volcanic and tectonic surface features, atmospheric energy balances, the greenhouse effect, and long-term climate dynamics.

Lithosphere

The rigid outer layer of a terrestrial world, consisting of the crust and the cool, uppermost portion of the mantle.

Differentiation

The process where gravity causes heavier materials like nickel and iron to sink inward toward the core while lighter silicate rocks float upward, releasing energy as interior heat.

Accretion Heating

Internal heating caused by the conversion of kinetic energy and gravitational potential energy into heat as material aggregated to form a planet.

Radioactive Decay

The continuous release of internal thermal energy over billions of years from radioactive isotopes like thorium and uranium at Earth's center, supplying approximately $7\%$ of Earth's heat.

Tidal Heating

Thermal energy generated by internal friction when a body's crust and interior layers are continuously flexed by the gravitational tides of a parent body.

Convection

A heat transfer mechanism inside planetary mantles where hot, lower-density rock rises toward the upper mantle and cooler, higher-density rock sinks.

Outgassing

The volcanic release of underground trapped gases into a planet's atmosphere, which provided Earth with much of its early $CO_2$ and water vapor.

Stratovolcano

A steep, cone-shaped mountain formed by viscous, thick lava containing low amounts of trapped gases (volatiles), often leading to explosive eruptions.

Shield Volcano

A broad volcano with a gently sloping, rounded profile formed by medium-viscosity lava containing some volatiles, resulting in frequent, non-explosive eruptions.

Volcanic Plains

Flat geological features produced by very runny lava containing large amounts of volatiles that spreads out without building mountain structures.

Planetary Resurfacing

A global event on Venus $500\text{--}750\text{ MYA}$ where internal pressure broke through the thick crust everywhere, resurfacing much of the planet in lava.

Plate Tectonics

The movement of rigid crustal plates across a planet's surface driven by mantle convection, requiring both thick continental and thin oceanic plates as well as water to act as a lubricant.

Albedo

The fraction of incoming solar radiation that is reflected back into space by a planet's surface or atmosphere.

Greenhouse Effect

The process where visible sunlight passes through an atmosphere to heat the surface, and outgoing thermal infrared radiation is absorbed and re-radiated by atmospheric gases.

Geoengineering

Intentionally altering Earth's environment on a global scale—such as increasing planetary albedo—to counteract temperature rise and climate change.

Cloud Brightening

A geoengineering approach of spraying sea salt aerosol into clouds from ocean vessels to increase cloud albedo and reflect incoming light back into space.

Carbon Cycle

The geological process where atmospheric $CO_2$ dissolves in rain, erodes rocks into sea carbonate sediments, subducts into the mantle, and is emitted back by volcanoes.

Quaternary Ice Age

The current geological ice age state that began $2.5\text{ million years ago}$, characterized by repeating glacial and interglacial periods.

Holocene Interglacial

The current warm interglacial phase within the Quaternary Ice Age that began approximately $10{,}000\text{ years ago}$.

Atmospheric Escape Velocity

The velocity threshold required for light gas molecules (like $H_2$ and $He$) to break free from a planet's gravitational pull into space.