Water
Budgets
Note: Each Water Budget is defined by three lines or
curves. A straight red line demarcates the temperature above which
the growth of most higher plants is possible -- namely 6º C. or
43º F., thus defining the "Growing Season". The two remaining
lines or curves define (1) the "Water Need" of the station, which is
a chiefly a function of temperature and thus produces a relatively
smooth line, and (2) the "Precipitation" or moisture actually
received by the station -- which may be a far more irregular line or
curve. A light-green identifies the times of the year when moisture
is received. Any time that the Precipitation exceeds the Water Need,
a surplus of moisture occurs, which is shown in blue on the diagram.
However, when the Precipitation is inadequate to meet the Water Need,
a deficit is recorded, which is shown in yellow on the diagram.
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