What are the scales of meteorology and how they are used

The concept of the scale of some phenomenon is common to physics, geography, astronomy, and, among others, meteorology.

The scale of meteorology is the spatial, but also the temporal scale of individual weather phenomena and their combination. In other words, when studying weather, meteorologists, as well as geographers and other scientists, use maps of different scales in order to better search, study, understand and predict these or those phenomena, focusing on a certain area whether it is a local phenomenon or the whole world. And this is very logical: to study a small weather event, it is important to immediately draw its boundaries, which cannot be exceeded; a bigger one — wider boundaries, and so on all the way around the world.

Hence, there are four main scientific scales, including meteorology: micro-, meso-, macro-, or synoptic, and mega-.

Important: we are talking about both horizontal weather scales from a few centimeters to the whole world, and vertical scales within the troposphere and the beginning of the stratosphere, that is, the first two layers of the atmosphere from the earth, which are actually where all weather phenomena are contained.

So in this article, we will deal with all four types of meteorological scales. Let us say at once that these divisions are somewhat conditional, their boundaries may be blurred, and they also may not coincide in exact values with similar scales in other sciences.

Microscale meteorology — small or local

Microscale meteorology or micrometeorology (as well as small or local meteorology) studies the smallest weather phenomena on a scale of a few centimeters to a kilometer or a bit more, which lasts no more than a day (24 hours).

For example, soil temperature in some small areas, certain features of clouds of particular types, short-lived thunderstorms, local turbulence, and others, but more importantly, their relationships with each other or how one passes into the other.

This also includes, for example, the study of individual air pollutants, which are taken into account in calculating the Air Quality Index (AQI). Specifically, there are top five air pollutants in the US are ground-level ozone, particle pollution, carbon monoxide, sulfur dioxide, and nitrogen dioxide. So this is the kind of weather phenomenon that cannot be depicted on a normal weather map. (Although there are air quality maps.)

Types of clouds. Valeriya Milovanova / Windy.app

Mesoscale meteorology — medium or regional

Mesoscale meteorology or mesometeorology (as well as medium or regional meteorology) studies medium-scale weather phenomena from a few kilometers to several hundred and a thousand or two, but usually not more, that last from one day to several days to a week.

For example, these are weather fronts or collision boundaries of air masses of different temperatures, which refer to convection processes (circulation) in the atmosphere. They are of two main types — cold and warm. Fronts bring with them certain weather, but above all speak of its variability. Weather fronts can be as large as a medium-sized U.S. state such as Ohio.

This also includes weather phenomena such as large thunderstorms, squall lines, sea and land breezes, vortexes, and others.

Cold fronts and warm weather fronts. Valeriya Milovanova / Windy.app

Synoptic scale meteorology — large or national and continental

Macroscale meteorology more commonly called synoptic scale meteorology or large scale meteorology (as well as national or continental) studies large-scale weather events of several hundred to several thousand kilometers that last up to several weeks. The word "synoptic", different from the other names, comes from the Greek word συνοπτικός (synoptikos), which means “seen together.”

For example, it is atmospheric pressure or the force with which a column of air presses against the surface at a particular place on the earth. Hence it can be low or high, and cover vast areas. Like the circulation of air masses, pressure is the essence of large-scale weather events or systems such as tropical cyclones (hurricanes in North America and typhoons in Asia), heat and cold waves, and others. Cyclones can be the size of several states in the southeast U.S. or several countries in East Asia, which they basically go through every year.

This also includes another, rarer variety of cyclones — extratropical cyclones or mid-latitude cyclones, with a more self-speaking name. They also carry severe gales, thunderstorms, blizzards, tornadoes, and other extreme weather events.

Cyclones formation in North Atlantic Ocean. Valeriya Milovanova / Windy.app

Megascale meteorology — largest or global

Megascale meteorology or megameteorology (as well as largest or global meteorology), as the name suggests, studies weather phenomena on a worldwide scale that last up to a month or more and occur continuously or with a certain periodicity, that is, they go from weather to climate (average weather over months, years, decades, and further down to millions of years).

For example, these are the global winds that blow around the globe. The two main types of global winds are trade winds, which blow all the time from the tropics to the equator, and monsoons, which change direction according to the seasons. It carries air masses of varying temperature and humidity, causing drought and rain. We emphasize again that global winds and other large-scale weather phenomena travel vast distances as they circle the earth (equatorial length is 40.075 km), and time intervals.

This also includes, say, El Niño in South America, which occurs once every five years and disrupts the usual atmospheric and oceanic processes.

Wind direction on the planet: global winds and west winds. Valeriya Milovanova / Windy.app

Four meteorological scales: comparison table

Let's summarize: when making regular weather forecasts that you read in your favorite app or website, meteorologists work mainly on two scales: meso- and synoptic with events up to a few thousand kilometers in size and lasting up to a few weeks. The other two scales, mirco and global, are used more often in special weather forecasts and in climate research, respectively. Here they are again:

Four meteorological scales. Valerya Milovanova / Windy.app

Microscale meteorology

Small or local
Centimeters to a few kilometers
Less than a day
Soil temperatures in a small area, cloud features, brief thunderstorms, local turbulence, air pollutants

Mesoscale meteorology

Medium or regional
Kilometers to 100s—1,000 kilometers
Days to weeks
Weather fronts, large thunderstorms, squall lines, sea and land breezes, vortexes, and others

Synoptic meteorology

Large or national and continental
100s to 1000s kilometers
Up to a month
High and low-pressure areas, tropical cyclones (hurricanes and typhoons), extratropical cyclones (mid-latitude cyclones)

Global meteorology