Geophysics & Environmental Physics
10 terms
Geoid
Geophysics & Environmental Physics
Meters (Geoid Undulation Height)
The hypothetical shape of Earth's surface defined by an equipotential surface of Earth's gravity field matching mean ocean sea level in the absence of tides and winds.
Equipotential Surface V_gravity = Constant
Geomagnetic Reversal
Geophysics & Environmental Physics
Geologic Time Interval
A major planetary event during which Earth's magnetic field undergoes a complete polarity flip, swapping magnetic North and South poles.
Reversal Interval ~ 200,000 to 300,000 years
Geomagnetic Storm
Geophysics & Environmental Physics
nT (Nanoteslas, Dst / Kp Index)
A major temporary disturbance of Earth's magnetosphere caused by solar wind shockwaves or Coronal Mass Ejections (CMEs).
Dst Index < -50 nT (Distortion of Equatorial Ring Current)
Geomagnetism
Geophysics & Environmental Physics
μT (Microteslas, ~30–60 μT at surface)
The scientific study of Earth's magnetic field, its internal origin in the liquid outer core, spatial variations, and temporal fluctuations.
B_geo = ∇ × A (Geodynamo Induction: ∂B/∂t = ∇ × (v × B) + η ∇²B)
Geostrophic Wind
Geophysics & Environmental Physics
m/s (Wind Velocity)
A theoretical atmospheric wind resulting from a exact balance between the horizontal Pressure Gradient Force and the Coriolis acceleration force.
v_g = (1 / (2 ρ Ω sin φ)) (dP / dn) = (1 / f ρ) ∇P
Geothermal Gradient
Geophysics & Environmental Physics
°C/km or K/km
The rate at which Earth's interior temperature increases with increasing depth below the surface.
q = -k (dT / dz) (Heat Flux = Conductivity × Gradient)
Glaciology
Geophysics & Environmental Physics
m/year (Glacier Flow Velocity)
The scientific study of glaciers, ice sheets, snow, and all natural ice phenomena in the cryosphere.
Glen's Flow Law: ε̇ = A τ^n (Non-linear ice creep)
Gravimetry
Geophysics & Environmental Physics
mGal (Milligals = 10⁻⁵ m/s²)
The precise measurement of spatial and temporal variations in Earth's gravitational acceleration field.
g_observed = g_theoretical + Δg_FreeAir - Δg_Bouguer + Δg_Terrain
Greenhouse Effect
Geophysics & Environmental Physics
°C or Kelvin (Warming Effect)
The thermodynamic warming process by which atmospheric greenhouse gases absorb outgoing infrared terrestrial radiation and re-emit it in all directions, raising surface temperatures.
T_surface = T_effective (1 + ¾ τ_IR)^(1/4) (Radiative Equilibrium)
Gutenberg Discontinuity
Geophysics & Environmental Physics
km (Boundary Depth)
The major geophysical boundary located at a depth of ~2,890 km marking the sharp transition between Earth's solid mantle and liquid outer core.
Depth z ≈ 2890 km (Core-Mantle Boundary D'' Layer)