dhdh's Climate Classification System (snowfall, hottest, warmest, averages)

[dhdh]

Since it seems that the new trend on the forum is to create climate classifications, I thought I'd take a shot at it. Mine is based mostly on Koppen but attempts to make it more detailed, especially on two points: the overly broad "C" winter category and rainfall distribution (where the creation of a B category for deserts is useless IMHO).

So basically:

• First letter indicates winter temperature
• Second letter indicates summer temperature
• Third letter indicates rainfall distribution (details follow)

For the first letter - winter:

A - Tropical: all months at or above 18°C (kept as it is)
B - Mild: coldest at or above 18°C, but above 10°C
C - Cool: coldest above 0°C, but below 10°C
D - Cold: coldest below freezing, but above -9°C
E - Severe: coldest at or below -9°C

The B/C distinction is used to separate the warmer end of Koppen's C climates - Hong Kong, Brisbane, Orlando - from the cooler end of the spectrum - Paris, Shanghai, Seattle - etc. while the letter E indicates winters colder than Montreal



Second letter - summer:

A - Sultry: warmest month at or above 30°C (for extremely hot summers such as the Middle East, Arizona, northern India, etc.)
B - Hot: 24°-30°C (for tropical and hot Med. climates)
C - Warm: 18-24°C (most European climates)
D - Cool: 12-18°C
E - Cold: 0-12°C


Polar climates (all months <0°C) are automatically assigned one single letter, F.

The use of A-E letters mirror the winter classification by dividing both seasons (winter and summer) into 5 representative categories, from hottest to coldest.



Third letter - rainfall distribution:

s - dry summer (as in Koppen)
w - dry winter (as in Koppen)
f - no dry season (as in Koppen)
d - semi-arid (as in Koppen)
D - desert (as in Koppen)



Additional precision for very wet months - sign to follow the three letters:

+ if wettest month is above 250mm (roughly 10 inches)
++ if wettest month is above 500mm

Therefore, s+ and w+ are hints of a monsoon climate.




EXAMPLES

Mecca: AAD
Singapore: ABf+
Goa: ABw++
Delhi: BAw+
Hong Kong: BBw+
Sydney: BCf
Los Angeles: BCs
Nice: CBs
Paris: CCf
London: CCf
NYC: CBf (borderline D)
San Francisco: CDs
La Paz: CDw
Reykjavik: CEf (borderline D)
Beijing: DBw+
Moscow: DCf
Fairbanks: EDf
Vostok: FD

(Calculated quickly, might've made a few mistakes)


Thoughts?

[ben86]

Hmm, that puts the London area in CCf in a separate climate zone to the rest of Britain in CDf then because of its warmer summers, which makes sense to be honest. Good system - I can't immediately spot any odd results it would throw up.

I checked Eureka to see if it would get in as a BDs and join the very select group of places that are two grades lower for summer than winter, but it doesn't average 10C in its coldest month (8.8C). Lerwick doesn't quite make it in as CEf either because August averages 12.2C.

[dhdh]

Well, oddities arise with borderline climates but I'm afraid that's something you can hardly avoid with quantitative classifications of that kind (unless you have a high number of letters, but then it would get confusing) - Nice and NYC are considered to have the same winters under that classification (but at least not Hong Kong/Brisbane and NYC/Turin - my main gripe with Koppen).

[dhdh]

Originally Posted by ben86

Hmm, that puts the London area in CCf in a separate climate zone to the rest of Britain in CDf then because of its warmer summers, which makes sense to be honest. Good system - I can't immediately spot any odd results it would throw up.

I checked Eureka to see if it would get in as BDs and join the very select group of places that are two grades lower for summer than winter, but it doesn't average 10C in its coldest month (8.8C). Lerwick doesn't quite make it in as CEf either because August is 12.2C.

Quito is BDf.
Now, finding a climate with a coolest and a warmest month both between 10°C and 12°C would be the real challenge and would result in a BE classification.

[Ariete]

Borderline DCf. Ok, makes sense.

[Glacierx]

Originally Posted by dhdh

Polar climates (all months <0°C) are automatically assigned one single letter, F.

[...]

Thoughts?

Ha ha. Like it, although I'm not a big fan of the Koppen precipitation classifications.

My location is DCd.

[ksolina]

Zagreb is DCf, 0.1c short of being CCf.

[kronan123]

A - Tropical: all months at or above 18°C (kept as it is)
B - Mild: coldest at or above 18°C, but above 10°C
C - Cool: coldest above 0°C, but below 10°
D - Cold: coldest below freezing, but above -9°C
E - Severe: coldest at or below -9°C

there's a huge difference between 0C and -9C climates in terms of snowcover, extreme low temperatures and so on. i'd split that up into four subcategories. also, the threshold for "severe winter" should be lowered.


here's my take on it.
D
cat1: 0 to -5C - slush winter climates. snow comes and goes for periods of weeks throughout the winter most of the winters.
cat2 -5C to -7C -real snow winters. snowpack that lasts for months most of the winters
cat3 -7C to -9C - real snow winters. snowpack that lasts for months almost all winters (except extremly mild ones)
cat4 -9C to -12C- real snow winters. snowpack last for months no matter how the winter turns out to be.

E -12C and below - severe snow winters. snowpack last for months no matter how the winter turns out to be. mild winters tend to increase the snowfall rather than reduce it.

[overdrive1979]

Dcs for me.

It would be better to add another word for refine dry summer climates.
Most of mediterranean climates of central and eastern Iberian peninsula have two almost equal rainiest seasons in both autumn and spring, while most mediterranean climates of the rest of the world have a single rainy peak in winter.

[Jakobsli]

Interesting suggestion, but a few comments:

Quote:

Summers:

B - Hot: 24°-30°C (for tropical and hot Med. climates)
C - Warm: 18-24°C (most European climates)
D - Cool: 12-18°C
E - Cold: 0-12°C


Polar climates (all months <0°C) are automatically assigned one single letter, F.

End of quote.

The big weak point about this system is that it classifies areas with boreal forest (warmest month 12C) in the same category as a polar tundra with warmest month 1C - which will have virtually zero vegetation.
If you look at those two landscapes, they would be very, very different, especially in summer. Since you have 6 degrees range for the other letters, why 12 degrees here?
The warmest summer month of ca 10C is one of nature's most important thresholds, as it roughly defines the treeline. Some oceanic areas migh have tree line as cool as 9C (such as Iceland), while some continental areas will have the treeline at a bit higher temperature than 10C, but 10C is roughly correct.
And the treeline is a very important threshold for other plants (shelter, etc) , animals and insects.


Also, Kronans point is a good one.
I would at least divide the 0 to -9C range for coldest winter month in two, with -4C as a possible threshold, as a lot starts to change when coldest month approaches 0C.