Meteorology is the scientific study of Earth's atmosphere, particularly its composition, structure, behaviour, weather and the physical processes responsible for atmospheric change. The word meteorology derives from Greek terminology associated with atmospheric phenomena and the study of things occurring in the air or heavens. Meteorology examines temperature, air pressure, humidity, wind, clouds, precipitation, atmospheric stability, radiation and storms.
Weather refers to the short term state of the atmosphere at a particular place and time, whereas climate concerns statistical patterns of atmospheric conditions over much longer periods. Meteorology therefore concentrates especially on atmospheric processes and weather phenomena, although meteorologists also contribute to climate research. The field combines physics, mathematics, chemistry, computer modelling, observation and data analysis to understand and predict atmospheric behaviour.
Earth's atmosphere is a layered mixture of gases dominated by nitrogen and oxygen, with smaller amounts of argon, carbon dioxide, water vapour and other gases. Meteorology examines how these components interact with solar radiation and Earth's surface. The atmosphere receives energy primarily from the Sun, but heating is uneven because Earth is spherical, rotates and has varying surface properties. Differences in heating create differences in temperature and pressure, which drive atmospheric circulation. Warm air can rise because of changes in density, while cooler air can sink. Water continually changes between vapour, liquid and solid forms, releasing or absorbing latent heat in the process. These interactions help produce clouds, precipitation, winds and storms.
Atmospheric pressure is a fundamental meteorological variable. Air has mass and therefore exerts pressure on surfaces beneath it. Pressure generally decreases with altitude because there is less air above. Horizontal pressure differences produce pressure gradients, and these gradients contribute to wind. Earth's rotation modifies moving air through the Coriolis effect, which causes apparent deflection relative to Earth's surface. Friction near the surface also influences wind speed and direction. Together, pressure gradients, Coriolis effects, friction, gravity and atmospheric structure contribute to the large scale circulation of the atmosphere. These principles help explain prevailing winds, jet streams, cyclones, anticyclones and many regional weather patterns.
Weather forecasting depends on observations collected from many different systems. Weather stations measure variables such as temperature, pressure, humidity and wind. Weather balloons carry instruments called radiosondes through the atmosphere to measure vertical profiles of temperature, pressure, humidity and wind. Radar detects precipitation and can provide information about the movement and intensity of storms. Satellites observe clouds, atmospheric moisture, temperature patterns and large scale weather systems from space. Aircraft, ships, buoys and other platforms provide additional measurements. These observations are combined to create an initial representation of the atmospheric state, which is then used in numerical weather prediction models.
Numerical weather prediction uses mathematical equations describing atmospheric motion, thermodynamics, radiation and moisture processes. Powerful computers solve approximations of these equations across a three dimensional grid covering a region or the globe. Because the atmosphere is a chaotic system, tiny differences in the initial state can eventually produce substantially different forecasts, especially at longer lead times. This limits perfect predictability. Meteorologists therefore use ensembles, in which multiple model simulations are run with varied initial conditions or model assumptions, to estimate uncertainty. Forecast skill is generally highest over shorter periods and decreases as the forecast horizon increases, although modern observations, models and computing have substantially improved forecasting capabilities.
Meteorology includes the study of many specific phenomena. Synoptic meteorology examines large scale weather systems such as fronts, depressions and anticyclones. Mesoscale meteorology focuses on phenomena ranging from thunderstorms to regional wind systems. Micrometeorology examines processes occurring close to the ground and over relatively small areas. Physical meteorology investigates radiation, clouds, precipitation and atmospheric thermodynamics. Dynamic meteorology applies fluid dynamics and mathematical physics to atmospheric motion. Severe weather meteorology studies hazards such as tornadoes, hurricanes, severe thunderstorms, hail, damaging winds and extreme precipitation. These specialisations overlap because weather phenomena operate across interacting spatial and temporal scales.
Meteorology has major practical applications because weather affects transport, agriculture, energy systems, construction, emergency planning, aviation, shipping and everyday activities. Accurate forecasts can provide warning of dangerous storms, heavy precipitation, high winds, freezing conditions, heatwaves and other hazards. Aviation meteorology is particularly important because aircraft operations depend on information about turbulence, icing, visibility, wind and thunderstorms. Renewable energy systems also depend on atmospheric conditions because wind and solar power output varies with weather. Agricultural meteorology helps farmers understand frost risk, rainfall, evaporation and growing conditions.
Meteorology is closely related to climatology but the disciplines are not identical. Meteorology generally investigates atmospheric processes and weather over shorter timescales, while climatology analyses long term statistics, patterns, variability and trends. Meteorologists may study an individual storm, whereas climatologists may study the frequency of storms over decades. Both rely on atmospheric physics and observations, and both increasingly use numerical models. Meteorology is therefore a foundational atmospheric science concerned with explaining and predicting the constantly changing state of the atmosphere, from local conditions and individual storms to global circulation patterns and extreme weather events.
