MONTHLY RAINFALL 1907
60
54,822
50
38,2396
40
10
33,4921 33,0677
29,2855
30
20
36,3981
18,81
4,75605
2,99025 2,88652
0,88287
2,76253
0
Q No 2
Seasonality in rainfall refers to the regular and predictable variations in the amount of
precipitation (rainfall) that occur over a specific time period. These variations are often
associated with natural climatic patterns and can have significant impacts on
ecosystems, agriculture, and water resources. Seasonal rainfall patterns can vary
widely depending on geographical location and climate. Here are some of the different
types of seasonality in rainfall that exist around the globe:
Monsoonal Seasonality: Monsoons are characterized by the reversal of wind patterns,
leading to distinct wet and dry seasons. In regions like South Asia, Southeast Asia, and
parts of Africa, monsoons bring heavy rainfall during the wet season, which is often
followed by a dry season with much less precipitation. These monsoonal rains are vital
for agriculture and water supply in these areas.
Tropical Seasonality: Tropical regions near the equator often experience two main
seasons: a wet season and a dry season. The wet season is associated with the
intertropical convergence zone (ITCZ) and features frequent and heavy rainfall, while
the dry season has significantly reduced precipitation.
Temperate Seasonality: In temperate regions, there are typically four distinct seasons:
spring, summer, autumn (fall), and winter. Rainfall is generally evenly distributed
throughout the year, with variations in temperature being more prominent.
Mediterranean Seasonality: Mediterranean climates, found in regions like Southern
California, parts of Australia, and the Mediterranean basin, experience wet winters and
dry summers. Most of the precipitation falls during the cooler months, with little to no
rainfall during the hot summer period.
Desert Seasonality: Desert regions, such as the Sahara Desert or the Atacama Desert,
often have extremely low and sporadic rainfall throughout the year. There may be
occasional rainy seasons, but they are typically short-lived and provide limited relief
from arid conditions.
Equatorial Seasonality: Near the equator, some regions experience fairly consistent
rainfall throughout the year, with minor fluctuations. These areas tend to have high
humidity and are often associated with lush tropical rainforests.
Polar Seasonality: In polar regions, such as the Arctic and Antarctica, precipitation
mainly occurs in the form of snow. These areas have extremely cold temperatures and
relatively low precipitation, which is typically concentrated during the warmer months.
Mountainous Seasonality: Mountainous regions can exhibit complex rainfall patterns
due to orographic effects. Windward sides of mountains tend to receive more rainfall,
while the leeward sides (rain shadows) experience drier conditions.
Seasonality in Pakistan:
In Pakistan, Monsoon seasonality occurs which is characterized by reversal of
wind patterns with distinct wet & dry patterns. Wet season occurred from Jan till April fol
by reversal of winds in Jun till August. Dry Season occurred from sept till December.
Q No 3
Seasonality Index
Seasonal Index is a measure of how a particular season through some cycle
compares with the average season of that cycle
Ser
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
Month
January
February
March
April
May
June
July
August
September
October
November
Rainfall
18.81
38.2396
29.2855
36.3981
4.75605
33.4921
33.0677
54.822
2.99025
2.88652
0.88287
SI
SI of Qtr
0.873555
1.775885
1.360048
1.690364
0.220876
1.555406
1.535697
2.545988
0.13887
0.134053
0.041001
1.424
1.4644
0.11
12.
December
2.76253
0.128295