acid soils and unfavorable glacial terrain in the
form of bogs and lakes, rocky hills, and stony
soils has deterred crop farming in many parts.
6.3
220 Hot Continental Division
South of the warm continental climate lies
another division in the humid tropical domain,
one with a humid, hot-summer continental climate. It has the same characteristics as the warm
continental except that it is more moderate and
has hot summers and cool winters (see Fig. 6.3,
climate diagram for Wien, Austria). The boundary between the two is the isotherm of 22
C for
the warmest month. In the warmer sections of the
humid temperate domain, the frost-free or growing season continues for 5–6 months, and in the
colder sections only 3–5 months. Snow cover is
deeper and lasts longer in the northerly areas.
This climate is located in central and eastern
parts of United States, northern China (including
Manchuria), Korea, northern Japan, and central
and eastern Europe.
In the Ko ¨ppen-Trewartha system, areas in this
division are classified as Dca (a signifies hot
summer). We include in the hot continental division the northern part of Ko ¨ppen’s Cf (subtropical) climate region in the eastern United States.
Ko ¨ppen used as the boundary between the C-D
climates the isotherm of À3
C for the coldest
month. Thus, for example, in the United States,
Ko ¨ppen places New Haven, Connecticut, and
Cleveland, Ohio, in the same climatic region as
New Orleans, Louisiana, and Tampa, Florida,
despite obvious contrasts in January mean
temperatures, soil groups, and natural vegetation
between these northern and southern zones.
Trewartha (1968) redefined the boundary
between C and D climates as the isotherm of
0
C of the coldest month, thereby pushing the
climate boundary south to a line extending
roughly from St. Louis to New York City.
Trewartha’s boundary is adopted here to distinguish between humid continental and humid subtropical climates.
Natural vegetation in this climate is winter
deciduous forest, dominated by tall broadleaf
trees that provide a continuous dense canopy in
summer, but shed their leaves completely in the
winter (Fig. 6.5). Lower layers of small trees and
shrubs are weakly developed. In spring, a luxuriant ground cover of herbs quickly develops, but
is greatly reduced after trees reach full foliage
and shade the ground. Common trees in eastern
United States, eastern Europe, and eastern Asia
are oak, beech, birch, hickory, walnut, maple,
basswood, elm, ash, tulip, sweet chestnut, and
hornbeam. Hemlock, a needleleaf evergreen
tree, may also be present.
Soils are chiefly red-yellow podzols
(Ultisols), and gray-brown podzols (Alfisols),
Fig. 6.4 Broadleaf deciduous and needleleaf evergreen
forest as it appears in the Lake States region of north
central United States. Photograph by Robert G. Bailey
Fig. 6.5 A stand of mature sugar maples in the
Allegheny National Forest, Pennsylvania. Photograph by
B.W. Muir, U.S. Forest Service
6.3 220 Hot Continental Division
59
form of bogs and lakes, rocky hills, and stony
soils has deterred crop farming in many parts.
6.3
220 Hot Continental Division
South of the warm continental climate lies
another division in the humid tropical domain,
one with a humid, hot-summer continental climate. It has the same characteristics as the warm
continental except that it is more moderate and
has hot summers and cool winters (see Fig. 6.3,
climate diagram for Wien, Austria). The boundary between the two is the isotherm of 22
C for
the warmest month. In the warmer sections of the
humid temperate domain, the frost-free or growing season continues for 5–6 months, and in the
colder sections only 3–5 months. Snow cover is
deeper and lasts longer in the northerly areas.
This climate is located in central and eastern
parts of United States, northern China (including
Manchuria), Korea, northern Japan, and central
and eastern Europe.
In the Ko ¨ppen-Trewartha system, areas in this
division are classified as Dca (a signifies hot
summer). We include in the hot continental division the northern part of Ko ¨ppen’s Cf (subtropical) climate region in the eastern United States.
Ko ¨ppen used as the boundary between the C-D
climates the isotherm of À3
C for the coldest
month. Thus, for example, in the United States,
Ko ¨ppen places New Haven, Connecticut, and
Cleveland, Ohio, in the same climatic region as
New Orleans, Louisiana, and Tampa, Florida,
despite obvious contrasts in January mean
temperatures, soil groups, and natural vegetation
between these northern and southern zones.
Trewartha (1968) redefined the boundary
between C and D climates as the isotherm of
0
C of the coldest month, thereby pushing the
climate boundary south to a line extending
roughly from St. Louis to New York City.
Trewartha’s boundary is adopted here to distinguish between humid continental and humid subtropical climates.
Natural vegetation in this climate is winter
deciduous forest, dominated by tall broadleaf
trees that provide a continuous dense canopy in
summer, but shed their leaves completely in the
winter (Fig. 6.5). Lower layers of small trees and
shrubs are weakly developed. In spring, a luxuriant ground cover of herbs quickly develops, but
is greatly reduced after trees reach full foliage
and shade the ground. Common trees in eastern
United States, eastern Europe, and eastern Asia
are oak, beech, birch, hickory, walnut, maple,
basswood, elm, ash, tulip, sweet chestnut, and
hornbeam. Hemlock, a needleleaf evergreen
tree, may also be present.
Soils are chiefly red-yellow podzols
(Ultisols), and gray-brown podzols (Alfisols),
Fig. 6.4 Broadleaf deciduous and needleleaf evergreen
forest as it appears in the Lake States region of north
central United States. Photograph by Robert G. Bailey
Fig. 6.5 A stand of mature sugar maples in the
Allegheny National Forest, Pennsylvania. Photograph by
B.W. Muir, U.S. Forest Service
6.3 220 Hot Continental Division
59