Climate Classification Flowchart

Climate Classification Flowchart

By: Matthew Goble

E Climates

ET (Tundra Climate): Average temperature of warmest month is between 0 and 10 degrees

EF (Perpetual frost): Average temperature of the warmest month is below 0 degrees

If the station does not belong to E climate, then test it for B climate

B Climates

Determine whether the station has uniform precipitation or summer dry or winter dry, using the following:

• Winter Dry: If at least 70% of the total annual precipitation occurs during the six summer months (April-September in the N.H.), then it has a winter dry regime
• Summer Dry: If at least 70% of the total annual precipitation occurs during the six winter months (October-March in the N.H.), then it has a summer dry regime
• If neither of the above criteria applies, then it has a uniform precipitation regime

Once you have found out the appropriate precipitation regime of the station, use one of the following equations that are relevant to your regime

B Climates

Summer Dry: r = 2T

Second Symbol: Calculate r', where r' = r/2

Winter Dry: r = 2(T+14)

• If B continue to second symbol
• If not B, skip next slide

Uniform: r = 2(T+7)

• If the total annual precipitation of a station is less than r', then it is a BW climate
• If it is greater than r', it is a BS climate

T = Annual Average Temperature in Degrees Celsius

Third Symbol: Any one of the following third symbols may be used for BS or BW

If the total annual precipitation of a station is less than r, then it is a B climate

• h (hot): Annual average temp. exceeds 18 degrees
• k (cold winter): Annual average temp. is less than 18 degrees
• k' (cold): Annual average temp. is less than 18 degrees and temp. of the warmest month is less than 18 degrees

A Climates

Temperature of the coldest month is 18 degrees or higher

A climate is divided into 3 subdivisions:

• Af: Rainfall in the driest month is at least 6cm or more
• Am: Rainfall in the driest month is less than 6cm but is greater than 10-(m/25), where m is annual rainfall in cm
• Aw: Rainfall in the driest month is less than 10-(m/25)

If the station is not A, then continue to Climates C and D

C and D Climates

C and D Climate

C and D Climates

Second Symbol: I (works for both C and D)

Second Symbol: III

Second Symbol: II

C: Temperature of the coldest month is below 8 degrees and above -3 degrees

Cf, Df: No marked dry season; uniform moisture throughout the year; therefore, neither of the above criteria is applicable

D: Temperature of the coldest month is below -3 degrees and the warmest month is above 10 degrees

Cw, Dw: The driest month occurs in the coldest six months, and the amount of precipitation in the driest month is less than 1/10th the amount in the wettest month of the warmest six months

Cs, Ds: The driest month occurs during the warmest six months (summer) and the amount of precipitation in the driest month is less than 1/3 of the amount in the wettest month of the coldest six months (winter). Also Precipitation during the driest month is less than 3cm. Temperature of the coldest month is below 18 degrees and above -3 degrees

C and D Climates

Third Symbol:

• a: Warmest month is 22 degrees or higher
• b: Warmest month is below 22 degrees but at least four months are above 10 degrees
• c: Only one to three months is above 10 degrees
• d: Coldest month is below -38 degrees