• Koppen Climate Classification System is widely used for classifying climate
• Wladimir Köppen, a Russian-German climatologist, created this system by studying the relationship between vegetation and climate
• He aimed to create a chart that showed the climatic boundaries with similarity to existing vegetation
• Köppen selected certain values of temperature and precipitation to classify climates
• He assigned alphabetical letters (A, B, C, D, E, and H) to classify the entire world’s climate
• These categories are further subdivided into smaller subdivisions and types using small letters (a, b, c, d, h, f, m, w, k, and s)
• Understanding the differences between weather and climate is important before discussing the Koppen Climate Classification System.

Differences between weather and climate

	Climate	Weather
Definition	Describes the average conditions expected at a specific place at a given time (considerable time). A region’s climate is generated by the climate system, which has five components: atmosphere, hydrosphere, cryosphere, land surface, and biosphere.	Describes the atmospheric conditions at a specific place at a specific point in time. Weather generally refers to day-to-day temperature and precipitation activity
Components	Climate may include precipitation, temperature, humidity, sunshine, wind velocity, phenomena such as fog, frost, and hail storms over a long period of time.	Weather includes sunshine, rain, cloud cover, winds, hail, snow, sleet, freezing rain, flooding, blizzards, ice storms, thunderstorms, steady rains from a cold front or warm front, excessive heat, heat waves and more
Forecast	By aggregates of weather statistics over periods of 30 years	By collecting meteorological data, like air temperature, pressure, humidity, solar radiation, wind speeds and direction etc.
Determining factors	Aggregating weather statistics over periods of 30 years (“climate normals”).	Real-time measurements of atmospheric pressure, temperature, wind speed and direction, humidity, precipitation, cloud cover, and other variables
About	Climate is defined as statistical weather information that describes the variation of weather at a given place for a specified interval.	Weather is the day-to-day state of the atmosphere, and its short-term (minutes to weeks) variation
Time period	Measured over a long period	Measured for short term
Study	Climatology	Meteorology

Koppen Climate Classification System

• Wladimir Köppen was a Russian-born German climatologist and amateur botanist
• He developed a climate classification scheme that was first published in 1918
• He continued to modify and refine the system until his death in 1940, with the last version being published in 1936
• The modified Köppen system describes five major climate groups: A, B, C, D, and E
• These major groups are further divided into a total of 14 individual climate types
• The system also includes a special category for highland (H) climates

• Koeppen recognized five major climatic groups, four of them are based on temperature and one on precipitation.
• The capital letters:
  • A, C, D, and E delineate humid climates and
  • B dry climates.
• The climatic groups are subdivided into types, designated by small letters, based on seasonality of precipitation and temperature characteristics.
• The seasons of dryness are indicated by the small letters: f, m, w, and s, where
  • f – no dry season,
  • m – monsoon climate,
  • w – winter dry season and
  • s – summer dry season.
• The above mentioned major climatic types are further subdivided depending upon the seasonal distribution of rainfall or degree of dryness or cold.
  • a: hot summer, the average temperature of the warmest month over 22°C
  • c: cool summer, the average temperature of the warmest month under 22°C
  • f: no dry season
  • w: the dry season in winter
  • s: the dry season in summer
  • g: Gange’s type of annual march of temperature; hottest month comes before the solstice and the summer rainy season.
  • h: average annual temperature under 18°C
  • m (monsoon): short dry season.
• The capital letters S and W are employed to designate the two subdivisions of dry climate:
  • semi-arid or Steppe (S) and
  • arid or desert (W).
• Capital letters T and F are similarly used to designate the two subdivisions of polar climate
  • tundra (T) and
  • icecap (F).

A – Tropical Moist Climates

• Tropical moist climates are found about 15 to 25 degrees latitude north and south of the equator.
• Temperatures in these zones remain above 18 degrees Celsius all year.
• Annual precipitation in this zone is usually above 1,500 mm.
• There are three minor climatic types within this zone based on the seasonal distribution of rainfall.
• The first is Af, or tropical wet climate, with precipitation all year round and monthly temperature variations of less than 3 degrees Celsius.
• The second is Am, or tropical monsoon climate, with most precipitation occurring within the 7 to 9 warmest months of the year and less rainfall in the rest of the year.
• The third is Aw, or the tropical wet and dry climate, or the savanna climate, with an extended dry season during the winter and less than 1,000 mm of precipitation during the wet season.

B – Dry Climates

• Temperature is not a major factor in these climatic zones.
• Evaporation and transpiration exceed the total precipitation.
• They extend 20 to 35 degrees latitude northwards and southwards from the equator.
• There are four sub-divisions of this climactic zone.
• The first is BW or the true desert climate, covering about 12% of the Earth’s land area, with xerophytic vegetation.
• The letters h and k are suffixed after BW to indicate the location of the zone in the sub-tropics or mid-latitudes.
• The second is BS or the steppe climate, which is present on about 14% of the Earth’s surface and receives more precipitation than BW.
• The letters h and k are suffixed in a similar way to BW zones to define the location of the climatic zone in the sub-tropics or in the mid-latitudes respectively.

C – Moist Sub-tropical Mid-latitude Climates

• This climactic zone has warm and humid summers and mild winters.
• It extends 30 to 50 degrees latitude north and south from the equator.
• It is mainly present at the eastern and western extremes of most continents.
• The zone features many convective thunderstorms in summer and some mid-latitude cyclones in winter.
• There are three subdivisions of this zone:
  • Humid subtropical climate (Cfa) with hot and humid summers and mild winters, with precipitation during this period occurring due to mid-latitude cyclones.
  • Cfb marine climate with humid climate, hot and dry summer, and mild winters accompanied by heavy precipitation due to mid-latitude cyclones.
  • Mediterranean climatic zone (Cs) with mostly mild winters, and rainfall during winter due to mid-latitude cyclones. Summer months can have very low precipitation.
• Some areas falling under this climatic zone include locations in Portland, Oregon, and California.

D – Moist Continental Mid-latitude Climates

• Summers are warm and can also be cool while winters are cold.
• Regions are usually located polewards from the moist sub-tropical mid-latitude climates or C climates.
• Average temperatures in the warmest months are usually more than 10 degrees C, while temperatures in the coldest months can be less than minus 3 degrees C.
• Winters can be bitterly cold, with strong winds and snowstorms that flow from the Continental Polar and the Arctic air masses.
• Three sub-divisions: Dw – with dry winters, Ds – with dry summers, and Df – with precipitation all year round.

E – Polar Climates

• Polar climates have low temperatures all year round, with the warmest month having temperatures less than 10 degrees C.
• They occur in northern coastal areas of Asia, Europe, and North America, as well as on Greenland and Antarctica.
• There are two sub-divisions:
• ET or Polar Tundra, where soil is permanently frozen as permafrost, and vegetation is mostly in the form of dwarf trees, woody shrubs, lichens, and mosses.
• EF or Polar Ice Caps, which have a surface permanently covered with ice or snow.

Pros of Koppen Classification

• Quantitative: easier to understand and measure
• Coincides with vegetation pattern
• Gave importance to effective precipitation (evapotranspiration)

Cons of Koppen Classification

• Koppen’s classification emphasizes mean monthly values of temperature and precipitation
• Precipitation factors can only be estimated, making comparison difficult
• Daily temperature variations, precipitation intensity, cloud cover, and number of rainy days were ignored
• Air masses, which are crucial to modern climatology, were not considered
• Koppen’s classification is empirical and based on observations, but ignores causative factors of climate
• It is not a genetic classification.