1. GI – 514
GEOINFORMATICS FOR CLIMATE CHANGE AND
ENVIRONMENTAL IMPACT ASSESSMENT
CLIMATIC PATTERN IN MOUNTAINS,
PLATEAU, COASTAL REGIONS –
Submitted by :
– Here we have discussed the different climatic patterns of mountains , plateaus and coastal region. We will come to
know the factors that influence the climatic conditions over these areas all over the world.
– We have also highlighted the climatic conditions in major mountain belts and plateaus of the world. Also realized
how climatic changes in Tibetan plateau and Himalayas are a big threat to the whole ecosystem.
– Lastly we have covered all the major points related to the climate of mountains , plateaus and coastal region and
how we can conserve the environment by sustainable development.
3. Mountain Climate
Factors affecting mountainous climate
Temperature and winds
– Mountains have predictable wind patterns, which interfere with the thermal stratification in a typical way.
Similar to the sea and land breeze in coastal areas, winds tends to blow from the highland into the valley at
night (contributing to the above-mentioned inversions), and from valley to mountain during the day.
– When winds are driven over the mountains or becomes heated by the sun ; the air rises, expands, forms
clouds and rain. As this air descends on the other (lee) side, it becomes compressed again, dries and warms
up. This wind can be a quite strong, gusty, and dry wind. This dry and warm wind is called the Föhn in
Europe, the 'Chinook' in the USA, Halny Waitr in Poland, the Zonda in Argentina and in New Zealand the
Nor’west arch. They are infamous for their ability to make snow melt rapidly due to their warmth and
– However as we have seen earlier not all downslope winds are warm. Even when air warms as it descends, it
can still be cooler than the air it is displacing. They can be biting cold and in France are called the
Mistral. It is the effect of topography, which is largely responsible for wind turbulence in mountains.
5. Solar Radiation
– Due to high elevation, low aerosol load and low moisture, solar energy undergoes
significantly less absorption by the atmosphere than in the lowlands. In addition, shade,
slope, and cloudiness play a dominant part in the spatial distribution of solar energy at
a given elevation, to the extent that solar energy input can easily vary by a factor of 100
from a permanently shaded valley bottom to a well exposed slope.
Figure 1: Amount of energy received by a sloping surface compared
with a horizontal surface (Northern Hemisphere, 45º latitude). The
abscissa indicates the slope in degrees, varying from 0º (horizontal)
to 90º (vertical), while the different curves show the effect of aspect,
i.e. the direction which is perpendicular to the surface points, e.g.
East and West indicates the energy received by surfaces that face the
East and those that face the West.
6. Rainfall and water balance
– Atmospheric water tends to precipitate when an air mass is lifted and cooled when it reaches a mountain range.
Windward slopes typically received significantly more rains than the leeward slopes. This is particularly
spectacular in monsoon climates when some stations at the foothills of the Himalayas are among the wettest
locations on Earth (Cherrapunji, India, 10600mm per year). The same phenomenon occurs as well in other
continents, albeit in a less spectacular fashion: la Vuelta, Colombia, records 9050 mm per year and Douala,
Cameroon, 3800 mm.
Mount Kilimanjaro, situated at 3 degrees Southern latitude, is exposed successively to
the SE monsoon and to the NE monsoon, resulting in the East facing-slopes being
significantly wetter than the Western ones, some of which are actually semi-arid.
Kilimanjaro illustrates another well known features of rainfall in mountains: once all the
precipitable water has been removed from the atmosphere, rainfall decreases again, so
that, similar to the "warm belt" just above temperature inversions, many mountains also
display a "wet belt", usually at elevations significantly higher than the "warm belt"
(figures 2a and 2b).
7. Elevation and Latitude
– When mountains are not very high, like most mountains on the African continent - except Kilimanjaro, the
temperature drop with elevation is not sufficient to remove all precipitable water from the atmosphere, with the
consequence that on average rainfall increases with elevation (annually, about 100 mm every 1000 m). In Asia and
South America, in spite of the wet belts, the general tendency is a decrease of rainfall with elevation, of the order of
300 mm every 1000 m in Asia and 100 mm per 1000 m in Latin America.
– Depending on elevation and latitude, a sizeable fraction of precipitation can be in the form of snow. In Europe, for
instance, elevations above 3600-3800 receive only snow. As with radiation, the effects described above result in the
precipitation climate of mountains to be characterised by a very marked spatial and temporal variability, including
dry valleys and dry plateaus at high elevations that would normally be expected to receive fair amounts of rainfall.
8. Alpine climate
The location, shape and variation in shape of the European Alps
gives rise to extreme changes in weather patterns across the Alps
and within regions of the Alps. Unlike the UK which is an island the
Alps are centrally located and are affected by four air flows
• The mild moist air from the Atlantic
• Cool or cold polar air from northern Europe
• Continental air masses, cold and dry in winter and hot in summer,
dominate the east of the Alps
• The southern Alps are affected by warm Mediterranean air that
The Himalaya is so big that the weather varies greatly
from one region to another. The Himalaya obstructs
the passage of cold continental air from the north into
India in winter and also forces the southwesterly
monsoon winds to give up most of their moisture
before crossing the range northward to Tibet.
There are two periods of rainfall/snow:
• the small amounts brought by winter storms and
• the heavier precipitation of the
southwesterly monsoon winds.
During winter, depressions advance from the west and
cause heavy snowfall, which is greatest over the high
mountains and is greater in the west than the east. In
January, for example, Mussoorie in the west receives
almost 7.5cm, whereas Darjeeling to the east receives
less than 2.5cm. By the end of May the situation is
reversed with southwesterly moist ‘monsoon’ air
moves toward the eastern Himalayas, where the
moisture rising over the steep terrain cools and
condenses to fall as rain or snow.
9. Plateau Climate
– Plateaus are built over millions of years as pieces of Earth's crust smash into each other, melt, and
gurgle back toward the surface. Some owe their creation to a single process; others have been subjected
to more than one during different epochs of Earth's history.
– The climate in which the Plateau peoples live is of the continental type. Temperatures range from −30
°F (−34 °C) in winter to 100 °F (38 °C) in summer. Precipitation is generally low and forms a snow
cover during the winter, particularly at higher altitudes. There are three different provinces of vegetation
in the region. The Middle Columbia area is a steppe of sagebrush and bunchgrass fringed by yellow
pine on higher levels.
– The Upper Columbia consists mainly of wooded areas, although grassland is found in river valleys. The
Fraser area is a semi-open coniferous forest interspersed with dry grassland and a partly maritime flora.
10. Formation of Plateaus
– Many plateaus form as magma deep inside the Earth pushes toward the
surface but fails to break through the crust. Instead, the magma lifts up
the large, flat, impenetrable rock above it. Geologists believe a cushion
of magma may have given the Colorado Plateau its final lift beginning
about ten million years ago.
– Plateaus also form in the ocean, such as the Mascarene Plateau in the
Indian Ocean, one of the few underwater features clearly visible from
space. It extends approximately 770 square miles (2,000 square
kilometers) between the Seychelles and Mauritius Islands.
– Other plateaus are created over time as wind and rain wear away the
side of an uplifted region, giving it geographic distinction from the
surrounding terrain. Wind and rain eventually wear plateaus down to
mesas and buttes and sculpt odd landforms like the arches and hoodoos
found in southern Utah's famed national parks.
View of the Grand Canyon , Arizona USA
11. Deccan Plateau climate
– Temperature : The average daily temperatures at Nashik is shown in the
figure left. Maximum temperatures average 28 degrees C in January and
build rapidly to 37 degrees C by May. They then drop rapidly with the
arrival of the monsoon but continue to average ca. 28 degrees C for the
remainder of the year. Daily minimum temperatures are unaffected by the
arrival of the monsoon and continue to rise until they peak in June.
Minimum daily temperatures never average below 10 degrees C, so there
is no dormant season and two harvests a year are possible, if not
– Rainfall : Monthly rainfall data is shown on the figure left. The yearly
rainfall typically totals ca. 700mm, but most of this rain falls in the
summer months with the arrival of the monsoon. The western Ghats serve
to shelter the Deccan Plateau from excessive rain (of Goa Region).
Following pruning in November, drip irrigation is common until
harvesting which usually takes place in late January to March.
12. Tibetan Plateau Climate
– Tibetan plateau is a high-altitude arid steppe interspersed with mountain
ranges and large brackish lakes. Annual precipitation ranges from 100 to 300
millimetres (3.9 to 11.8 in) and falls mainly as hail. The southern and eastern
edges of the steppe have grasslands which can sustainably support
populations of nomadic herdsmen, although frost occurs for six months of the
year. Permafrost occurs over extensive parts of the plateau.
– Proceeding to the north and northwest, the plateau becomes progressively
higher, colder and drier, until reaching the remote Changtang region in the
northwestern part of the plateau. Here the average altitude exceeds 5,000
metres (16,000 ft) and winter temperatures can drop to −40 °C (−40 °F). As a
result of this extremely inhospitable environment, the Changthang region
(together with the adjoining Kekexili region) is the least populous region in
Asia, and the third least populous area in the world after Antarctica and
NASA satellite image of the south-eastern area of Tibetan Plateau.
Brahmaputra River is in the lower right (earthobservatory.nasa.gov)
13. Glaciation and climate change in the
– Today, Tibet is an important heating surface of the atmosphere. With a much lower latitude,
the ice in Tibet reflected at least four times more radiation energy per unit area into space
than ice at higher latitudes. Thus, while the modern plateau heats the overlying atmosphere,
during the Last Ice Age it helped to cool it.
– This cooling had multiple effects on regional climate. Without the thermal low pressure
caused by the heating, there was no monsoon over the Indian subcontinent. This lack of
monsoon caused extensive rainfall over the Sahara, expansion of the Thar Desert, more
dust deposited into the Arabian Sea, and a lowering of the biotic life zones on the Indian
subcontinent. Animals responded to this shift in climate, with the Javan rusa migrating into
– The Tibetan Plateau contains the world's third-largest store of ice. Temperatures are rising
four times faster than elsewhere in China, and the Tibetan glaciers are retreating at a higher
speed than in any other part of the world. ... In the long run, the glaciers are vital lifelines
for Asian rivers, including the Indus and the Ganges. Once they vanish, water supplies in
those regions will be in peril.
Natural-colour satellite image of the Tibetan
14. Coastal Region climate
– The climate of a coastal region is characterized by several weather conditions, which
combine to form atmospheric conditions that are unique to areas in and around the coast.
– The best way to describe a coastal climate is to first list the various weather conditions
that define it, and then look at each one in more detail. The primary weather conditions
that are associated with a coastal region are:
– Sea Breeze During The Day
– Land Breeze In The Evenings
– Moderate Climate Throughout The Year
– Coastal Fog
– Higher Rainfall Than Inland Areas
– Coastal regions where a desert meets the ocean can also have a vastly different climate.
For example, The Skeleton Coast in the Namid Desert, and the Atacama Desert in Chile
are some of the driest regions in the world.
15. Characteristics of coastal climate
Sea Breeze During The Day
– During the day, both the land and ocean warm up, but the land warms up much faster than the
waters of the sea. As you will discover, it is important to note that even though the ocean takes
longer to warm up, it is also able to retain the heat much longer than the land.
– As the land warms up, it heats the air at the surface. The warm air rises and expands which
leaves less air at the surface, creating a low-pressure system over land. Since water over the
ocean takes longer to warm up, it allows the air above it to maintain a higher pressure.
– Since air always flows from a high-pressure to a low-pressure system, the air from the ocean
flows to the land. This forms the sea breeze we are so familiar with, which usually occurs during
the afternoons and early evenings.
– Depending on the contrast in temperature between land and sea, the wind blowing from the
ocean may vary from a light breeze to relatively strong gusty wind.
16. Land Breeze In The Evenings
– During the evening, the opposite occurs. The land cools off much faster than the ocean, which retains
the heat, absorbed during the day, much longer. (The reason why I highlighted this ability of the ocean
in the previous section.)
– As a result, the colder air over land forms a high-pressure system, while the warm air over the sea
water rises and creates a low-pressure system.
– The wind now blows from the high-pressure area over land, to the low-pressure area over the sea.
This is how a land breeze is formed, which usually occurs late in the evening and the early hours of
Moderate Climate Throughout The Year
– The fact that the ocean takes much longer to warm up than land, and its ability to retain heat much
longer than as well, do not just play a role in the creation of land and sea breezes but are also
responsible for the moderate climate of coastal regions.
– During the summer season, the air temperature over land warms up fairly quickly, while the ocean
remains relatively cold since it takes longer to absorb the heat. During the winter months, the land
cools down faster than the ocean, which it is able to retain its heat longer.
– This results in cooler air moving in from the ocean during the summer, and warmer air over the sea,
that is blown inland during winter months. This creates a more moderate climate where the summers
are cooler, and the winters milder than inland regions.
17. Higher Rainfall Than Inland Areas
– Coastal regions normally have higher average rainfall than inland areas. It may seem obvious since
a large body of water and moisture is present at the coast. It is not always that simple, as moist
warm air must cool down sufficiently to condensate and form precipitation.
Two factors help this process along :
– Cold Land Temperatures
– Mountainous Terrain
– Very often, the coast is next to mountainous terrain. As the moist air from the ocean starts to rise
against the mountain, it starts cooling down. When it reaches dewpoint, condensation takes place
and rain falls on the coastal side of the mountain.
– This scenario often leads to areas with high rainfall on the windward side, and dry, warm weather
on the leeward side of a mountain near the coast. The Chinook Winds in North America are a
perfect example of this phenomenon.
– The mountains, plateaus and coastal region have some very unique climatic conditions that will be familiar
to anyone living in or have frequently those areas.
– Simply by looking at the characteristics of the different climatic conditions, we will be able to see what a
big influence the mountains , plateaus and coastal region have on almost every aspect of the climate.
– If you were unsure before, you will now have a good understanding of what can be the climate in
mountains, plateaus and coastal region, and why you will find certain atmospheric conditions that are so
unique to these areas.
– Moreover we are also witnessing serious climatic changes in all these three regions. For eg. Temperatures
are rising four times faster than elsewhere in China, and the Tibetan glaciers are retreating at a higher speed
than in any other part of the world. ... In the short term, this will cause lakes to expand and bring floods and
mudflows. ... In the long run, the glaciers are vital lifelines for rivers, including the Indus and the Ganges.
Once they vanish, water supplies in those regions will be in peril.