Earth's Climate System and History

Flashcards covering the fundamentals of climate science, Earth systems, geological history, and the radiative mechanisms driving climate change.

Weather

The immediate state of the atmosphere over short timeframes spanning hours to weeks, characterized by temperature, humidity, wind velocity, and precipitation.

Climate

The statistical description of the state, variability, and extremes of the climate system over a long time window, typically defined as a minimum of 30 years.

Climate Change

A persistent shift in the mean state, variability, or extremes of the climate system that lasts for decades or longer, caused by natural or human-induced factors.

Atmosphere

The thin layer made up of a mixture of gases and particles (predominantly $N_2$, $O_2$, $A$, $CO_2$, and $H_2O$) suspended in the air that surround the Earth.

Hydrosphere

The sphere of the Earth System that includes the liquid ocean, inland water bodies, and groundwater.

Cryosphere

A subset of the Hydrosphere consisting of frozen water, including polar ice-caps, sea-ice, permafrost, seasonal snow cover, and mountain glaciers.

Geosphere

The sphere that includes the solid Earth, comprising the core, mantle, crust, and soil layers.

Biosphere

The sphere including all of Earth's organisms, such as humans, and matter that has not yet decomposed.

Albedo

The measure of how much sunlight is reflected by a surface, ranging from $0$ (perfect absorption) to $1$ (perfectly white, mirror-like reflection).

Latent Heat Flux

The transfer of heat energy from Earth's surface to the atmosphere associated with the evaporation of water or sublimation of ice and its subsequent condensation.

Carbon Cycling

The continuous process where carbon moves between the atmosphere, oceans, soil, and living organisms through natural mechanisms.

Red Beds

Sedimentary rock formations that serve as geological clues for ancient aridity in regions that are presently humid, such as England and New England.

The Croll Hypothesis

The astronomical theory proposed in 1864 stating that cyclic variations in Earth's orbit alter solar radiation levels, triggering feedback loops like the ice-albedo effect to cause ice ages.

Eccentricity

One of the three Milankovitch Cycles involving changes in the Earth's orbit occurring over $100,000$ and $413,000$-year cycles.

Axial Tilt / Obliquity

A Milankovitch Cycle characterized by a $41,000$-year periodic change in the angle of the Earth's axis.

Precession of the Equinoxes

A Milankovitch Cycle referring to the change in the orientation of Earth's rotational axis over a $26,000$-year cycle.

Solar Luminosity

The total energy the Sun radiates into space every second, defined as precisely $3.828 \times 10^{26} Watts$.

Sunspot Cycles

An approximate 11-year periodic change in the Sun's magnetic activity, ranging from solar minimum to solar maximum.

Maunder Minimum

A period of extremely low sunspot frequency between 1645 and 1715 that corresponds with the historical cooling period known as the Little Ice Age.

Volcanic Outgassing

A warming mechanism that releases trapped carbon dioxide ($CO_2$) from Earth's interior into the atmosphere via eruptions and mid-ocean ridges.

Silicate Weathering

A negative feedback loop where acidic rain breaks down silicate rocks, removing carbon dioxide ($CO_2$) from the atmosphere and contributing to global cooling.

Volcanic Aerosol Cooling

A short-term natural forcing where explosive eruptions blast sulfur dioxide ($SO_2$) into the stratosphere, forming reflective sulfate aerosols that block sunlight.

Greenhouse Effect

The process where atmospheric gases like carbon dioxide ($CO_2$), methane ($CH_4$), and water vapor trap heat near Earth's surface by absorbing and re-radiating infrared radiation.