Meteopedia — Weather glossary
Weather encyclopedia with 342 terms
Browse detailed definitions of atmospheric phenomena, cloud types, measurement instruments, regional winds, meteorological scales, climatology and more.
A
Albedo
Fraction of solar radiation reflected by a surface, expressed from 0 (absorbs all) to 1 (reflects all).
ClimatologyAMOC
Atlantic Meridional Overturning Circulation: a system of currents that transports warm water northward and cold water southward in the Atlantic Ocean.
ClimatologyArctic amplification
Phenomenon whereby the Arctic warms 2-4 times faster than the global average, with profound consequences for atmospheric circulation.
ClimatologyAridity index
Numerical indicator classifying climatic zones according to the ratio between precipitation and potential evapotranspiration.
ClimatologyC
Carbon footprint
Total amount of greenhouse gases emitted directly and indirectly by a person, organisation, event, or product, expressed in tonnes of CO₂ equivalent.
ClimatologyClimate change
Significant, lasting change in global climate patterns, currently driven by greenhouse gas emissions.
ClimatologyClimate normal
Average of a meteorological variable calculated over a standard 30-year period (currently 1991–2020), used as a reference to compare current weather.
ClimatologyClimate sensitivity
Global warming resulting from doubling atmospheric CO₂ concentration from pre-industrial levels, estimated at 2.5–4 °C.
ClimatologyClimate tipping point
Critical threshold in the climate system beyond which a change becomes self-sustaining and irreversible, such as Greenland ice collapse or Amazon dieback.
ClimatologyContinental climate
Climate type with large temperature contrasts between summer and winter, moderate precipitation, and distance from oceanic influence.
ClimatologyD
I
Ice age
Prolonged geological period of low global temperatures with expansion of ice caps and glaciers, regulated by Milankovitch cycles.
ClimatologyIce-albedo feedback
Positive feedback loop where melting ice reduces surface albedo, increases solar radiation absorption, and accelerates warming and further melting.
ClimatologyIntertropical Convergence Zone
An equatorial low-pressure belt where the northern and southern trade winds converge, generating intense convection and rainfall.
ClimatologyM
Madden-Julian Oscillation
Pattern of tropical convection that propagates eastward every 30-60 days, modulating rainfall and storm activity on a global scale.
ClimatologyMediterranean climate
Climate type with hot, dry summers and mild, wet winters, found on Mediterranean coasts, California, Chile, South Africa, and western Australia.
ClimatologyMicroclimate
Particular climatic conditions of a very small area that differ from the general climate of the region, shaped by topography, vegetation, water, or urbanisation.
ClimatologyMilankovitch cycles
Periodic variations in Earth's orbit and axial tilt that regulate glacial and interglacial cycles over tens of thousands of years.
ClimatologyP
Pacific Decadal Oscillation
Climate pattern of North Pacific sea surface temperature variation with 20–30-year cycles, modulating fisheries, rainfall, and El Niño frequency.
ClimatologyPermafrost
Ground remaining frozen for at least two consecutive years, found in polar and high-mountain regions, containing enormous reserves of organic carbon.
ClimatologyPolar climate
Climate type with warmest month mean temperature below 10 °C, with permanently frozen ground or ice cover throughout the year.
ClimatologyR
Radiative forcing
Difference between solar energy absorbed by Earth and energy radiated back to space, caused by changes in greenhouse gases, aerosols, or albedo.
ClimatologyReturn period
Average time interval between occurrences of extreme events of equal or greater magnitude, used in engineering and planning.
ClimatologyT
Teleconnection
Statistical correlation between climate anomalies in geographically distant regions, linked through atmospheric circulation patterns.
ClimatologyTemperature anomaly
Deviation of temperature from the climate normal for a given date and location, expressed in positive degrees (warmer) or negative degrees (cooler).
ClimatologyThermohaline circulation
The global system of deep ocean currents driven by differences in water temperature and salinity.
ClimatologyTropical climate
Climate type with monthly mean temperatures above 18 °C year-round and abundant precipitation, with no defined cold season.
Climatology