Q. Briefly mention the alignment of major mountain ranges of the world and explain their impact on local weather conditions, with examples.

Model Answer: 

Mountains act as massive topographical barriers, significantly altering global atmospheric circulation and shaping local micro-climates depending on their latitudinal position and tectonic alignment.

Alignment of Major Mountain Ranges

• North-South Orientation: Predominantly located along the western or eastern margins of continents (Rockies, Andes, Great Dividing Range, Urals).
• East-West Orientation: Typically concentrated along major Eurasian tectonic plate boundaries (Himalayas, Alps, Atlas, Caucasus).

Impact on Local Weather Conditions

• Orographic Precipitation: Mountains force moisture-laden winds upward, causing intense, localized rainfall on windward slopes (Western Ghats intercepting the South-West Monsoon).
• Rain-Shadow Effect: Descending winds on leeward sides create distinct arid zones and continental deserts (Patagonian Desert via Andes; Death Valley via Sierra Nevada).
• Thermal Shielding: East-West ranges effectively block frigid polar winds, preserving warmer climates in southern latitudes (Himalayas protecting India from harsh Siberian winters).

• Meridional Wind Channeling: North-South alignments allow an unimpeded flow of extreme air masses across latitudes (Rockies funneling polar blizzards deep into the southern USA).
• Adiabatic Local Winds: Descending leeward winds undergo compressional heating, rapidly raising local temperatures and melting snow (Chinook winds in the Rockies; Foehn in the Alps).
• Monsoonal Deflection: Massive ridges mechanically steer planetary winds, completely altering regional precipitation distribution (Arakan Yoma deflecting monsoon winds towards the Indo-Gangetic plain).
• Valley Inversions: Differential diurnal heating creates localized katabatic (downslope) and anabatic winds, drastically modifying local microclimates (severe frost pockets in deep Himalayan valleys).

Thus, mountain alignments serve as pivotal geographic determinants, functioning as critical climatic divides that fundamentally orchestrate regional hydrology, biomes, and human settlement patterns globally.