If you can change the Koppen climate rules, what would you change?

[bbwillias]

Originally Posted by Mr.Sir

Cfa should be split into Subtropical and Temperate, NYC and Orlando should not be the same climate. Arid climates should be split into temperature zones, at least more than two. Finally, climates with low seasonal variation that are too cool to be tropical should have their own classification.

There not.

Check the Trewartha climate classification system....NYC is temperate (Dca) and Orlando in humid Subtropical (Cfa).

Your referring to the old Koppen system which really is not in use anymore

[Mr.Sir]

Originally Posted by bbwillias

There not.

Check the Trewartha climate classification system....NYC is temperate (Dca) and Orlando in humid Subtropical (Cfa).

Your referring to the old Koppen system which really is not in use anymore

Trewartha isn't Koppen. But it is true that Trewartha fixed that issue

[Infamous92]

The only changes I'd make would be to divide the larger definitions, such as subtropical, into different subtypes.

Originally Posted by bbwillias

There not.

Check the Trewartha climate classification system....NYC is temperate (Dca) and Orlando in humid Subtropical (Cfa).

Your referring to the old Koppen system which really is not in use anymore

NYC is still borderline subtropical under Trewartha, so it isn't much different than Köppen.

[nmdesert]

Koppen needs help, and Trewartha or Geiger aren't enough help nor are there detailed maps to tell much. But no matter what, the division between milder winters and colder winters should use 32F / 0C, not -3C or +3C no matter some other shifts depending on season of max precip, cloudiness, etc.

1) Split "subtropical" into "warm temperate" and "subtropical", since there's a notable difference in winter hard freezes and summer heat extremes in the wetter east or drier interior west. The split could be at the 64.4F / 18C as the minimum annual mean temperature. That would mean Oklahoma City or Nashville would be warm temperate and different classifications than subtropical Austin TX or Mobile AL. The same would occur in the dry zones with Albuquerque and El Paso being warm temperate arid and different than subtropical arid Phoenix.

2) Modify tropical "A" climates: perhaps retain 64.4F / 18C as the minimum coldest month temperature, but add there should be no month that has a record low temperature below 32F. Possibly a 40-45F record low, depending on the plants one wants to consider. Also, create a semi-arid and an arid subzone within "A". That would mean:
Cwa: Miami
As-: Honolulu, portions of the Sahara Desert and Arabian Peninsula

3) Split out all the continental humid climates (D-- and Cfa) into humid forest and sub-humid prairie / woodland, as Lincoln or Wichita Falls are considerably drier and do have a dry mid-summer than comparable temperature places without that dryness like Pittsburgh or Birmingham AL.

4) Not sure how to do this, but an east coast version of the above #3 might be in order, if Boston MA or Norfolk VA are different enough from Pittsburgh or Birmingham AL, respectively. Seems anywhere there are mountain ranges on east coasts at mid-latitudes have such a change.

[Bisfbath]

Koppen's Af category is a bit of a mess in my opinion. His 60 mm driest month is too strict as it excludes many places especially in Amazonia which are generally agreed to grow tropical rainforest. Ecologists seem to prefer no more than 2-3 months with less than 100 mm of rain. On the other hand his 18C coldest month is too lax and lets climates that are really too cool to be considered tropical rainforest, for example Andean equatorial climates where every month is barely warmer than 18C.

[Sun Belt-lover L.A.M.]

Part I: Tropical Climates

Spoiler

Places with a winter mean between 10C/50F and 18C/64.4F deserve to be considered semi-tropical. They have a different feel than subtropical places due to ability to grow *some* tropical plants like citrus, as well as being able to support tree growth year-round given sufficient precipitation.

Split said semi-tropical climates between mild-summer (e.g. Auckland, San Francisco) and hot-summer (e.g. Buenos Aires, Phoenix), using the 22C/71.6F summer isotherm. End tropical climates in -Y for hot-summer semi-tropical and -Z for mild-summer semi-tropical (including the hyphens prior to Y and Z). Apply the -Y and -Z AFTER the Mean Annual Temperature letter (see below).

Apply tropical precipitation standards to semi-tropical climates, not temperate/subtropical ones.

Change the requirements for tropical (and semi-tropical) rainforests to require 80 inches of rain annually and 4 inches in every month.

Split Am climates into Amw for dry winters and Ams for dry summers. Rename the dry-summer Ams to (Semi-)Tropical Mediterranean Climate, with Aw/As (Semi-)Tropical (Monsoon/Mediterranean) Savanna. There are quite a few dry-summer tropical climates, especially near the edges of the tropics where they border Mediterranean climates (e.g. parts of Mexico) or are in a rain shadow (e.g. parts of Hawaii).

Part II: Arid Climates

Spoiler

First and foremost, ENFORCE NORMAL TEMPERATURE CLASSIFICATIONS UPON ALL CLIMATES!

Now, moving on from my pleading scream for fairness, arid climates should maybe be split into three parts instead of two. Those should be steppe for 75-125% of the precipitation threshold, semi-desert for 25-75% and extreme desert for less than 25%.

Remove the constant from the precipitation threshold. No climate with a subfreezing mean annual temperature deserves to be considered arid, as permafrost is a much bigger problem than drought for plants adapted to such climates; evaporation is negligible in those areas for at least six months, almost always seven or more.

Part III: Mean Annual Temperature

Spoiler

Split mean annual temperature classifications, adding an extra letter to the end.
M: Megathermal, over 27C/80.6F
H: Hot, 18C/64.4F to 27C/80.6F
W: Warm, 14C/57.2F to 18C/64.4F
T: Mesothermal, 10C/50F to 14C/57.2F
K: Cold, 0C/32F to 10C/50F
C: Microthermal, under 0C/32F

Have this end letter apply to ALL climates regardless of other classification and precipitation.

Part IV: Subtropical and Temperate Climates

Spoiler

Apply the 8 months over 10C/50F as the isotherm between subtropical and warm temperate climates, with climates under -3C/26.6F being continental and under 3C/37.4F transitional regardless of the growing season length. Use S for subtropical, W for warm temperate, T for transitional and C for continental.

Apply the Apply the -a and -b letters for hot/mild summers AFTER the Mean Annual Temperature letter (see above), including the hyphens.

Add a rainforest precipitation category for these non-tropical climates too, with minimums of 60 inches annually and 3 inches in the driest month.

Rename any climates with w or s in them to be Monsoon or Mediterranean, not Humid.

Part V: Subpolar and Polar Climates

Spoiler

Apply the same precipitation thresholds as temperate and subtropical climates to polar climates, and keep them for subpolar.

Add the -a and -b to the end for subpolar climates (see temperate and subtropical climates); parts of Siberia are expected to have Dfa and Dfd climates bordering one another by century's end.

Keep the 0C/32F isotherm for distinguishing ice cap from tundra in summer and subpolar oceanic from subpolar continental in winter. Keep the hypercontinental classification for subpolar climates. Add the oceanic, continental and hypercontinental classifications for polar climates too (although oceanic couldn't apply to ice cap).