Atmosphere & Weather — Set 2

Correct Answer: C. To the Right

• **Coriolis Force (Northern Hemisphere)** = deflects moving objects including winds to the right due to Earth's rotation on its axis. • **Right deflection** — causes cyclones to rotate counterclockwise and anticyclones clockwise in the Northern Hemisphere. • 💡 Wrong-option analysis: To the Left: correct for Southern Hemisphere, not Northern; Upwards: Coriolis acts horizontally, not vertically; Downwards: Coriolis does not act in the vertical direction.

Correct Answer: B. Westerlies

• **Westerlies** = planetary winds blowing from Subtropical High (~30°) towards Subpolar Low (~60°), responsible for weather movement in temperate regions. • **Southwest direction** — in the Northern Hemisphere and northwest in the Southern Hemisphere, due to Coriolis deflection. • 💡 Wrong-option analysis: Polar Easterlies: blow from polar highs towards subpolar lows; Trade Winds: blow from subtropical highs towards equatorial low; Monsoons: seasonal winds, not planetary/permanent winds.

Correct Answer: A. Night

• **Land Breeze** = a local wind that blows from land to sea during the night, as land cools faster than sea, creating high pressure over land. • **Night cooling** — land radiates heat faster than the sea, reversing the daytime pressure gradient and driving cool air seaward. • 💡 Wrong-option analysis: Evening: transition period, neither sea breeze nor land breeze fully established; Morning: sea breeze begins as land heats up; Afternoon: peak time for sea breeze, not land breeze.

Correct Answer: C. Warm and Dry

• **Chinook** = a warm and dry local wind that flows down the eastern slopes of the Rocky Mountains in North America. • **'Snow Eater'** — Chinook's nickname because it rapidly melts snow due to adiabatic warming as air descends the mountain slopes. • 💡 Wrong-option analysis: Cold and Humid: opposite of Chinook characteristics; Warm and Humid: Chinook loses moisture on windward side, arrives dry; Cold and Dry: Chinook is warming, not cooling.

Correct Answer: B. Temperature

• **Temperature** = directly determines air's moisture-holding capacity; warmer air can hold significantly more water vapor than cooler air. • **Condensation** — occurs when warm moist air is cooled below dew point, as its capacity to hold vapor decreases with falling temperature. • 💡 Wrong-option analysis: Pressure: higher pressure slightly compresses air but does not increase moisture capacity; Altitude: higher altitude means cooler temperatures and lower moisture capacity; Wind speed: affects evaporation rate but not air's inherent moisture capacity.

Correct Answer: B. Dew Point

• **Dew Point** = the temperature at which air becomes fully saturated (100% relative humidity) and water vapor begins to condense into liquid. • **100% relative humidity** — the saturation threshold; below the dew point temperature, condensation as dew, fog, or clouds occurs. • 💡 Wrong-option analysis: Boiling Point: temperature at which water turns to vapor (100°C at sea level); Critical Point: thermodynamic state beyond which liquid/gas phases cannot be distinguished; Freezing Point: temperature at which water solidifies (0°C).

Correct Answer: A. Cirrostratus

• **Cirrostratus** = thin, transparent, high-altitude clouds composed of ice crystals that refract light to create a visible halo around the sun or moon. • **Ice crystals** — the composition of cirrostratus clouds that refracts sunlight/moonlight at 22° angles to produce the characteristic halo effect. • 💡 Wrong-option analysis: Stratus: low-lying gray layer clouds, no halo formation; Nimbostratus: dark rain clouds blocking sunlight completely; Cumulus: fluffy cotton-wool clouds at medium altitude, no halo.

Correct Answer: D. Nimbostratus

• **Nimbostratus** = thick, dark, shapeless cloud layers that produce continuous precipitation and completely block out the sun. • **Continuous rain** — the defining characteristic of nimbostratus; unlike cumulonimbus, they produce steady prolonged rainfall rather than intense showers. • 💡 Wrong-option analysis: Cirrocumulus: high-altitude white patchy clouds, no significant rain; Cirrus: wispy ice-crystal clouds, indicate weather change but no rain; Altocumulus: mid-level gray/white clouds, light rain at most.

Correct Answer: B. Convectional Rainfall

• **Convectional Rainfall** = rainfall caused when heated ground warms the air above it, causing it to rise, cool, and condense, common in equatorial regions. • **Equatorial regions** — experience daily convectional rainfall as intense solar heating drives strong vertical air movement; often accompanied by thunder and lightning. • 💡 Wrong-option analysis: Frontal Rainfall: occurs at boundaries between warm and cold air masses; Cyclonic Rainfall: associated with low-pressure systems; Orographic Rainfall: caused by mountains forcing moist air to rise.

Correct Answer: C. Leeward side

• **Leeward side (Rain Shadow)** = the side of a mountain that receives significantly less rainfall as descending air warms and loses its remaining moisture. • **Rain shadow area** — formed because moist air loses all precipitation on the windward (upwind) side while descending dry air on the leeward side creates arid conditions. • 💡 Wrong-option analysis: Windward side: faces incoming moist wind, receives heavy orographic rainfall; Summit: the peak, receives maximum precipitation; Upslope side: another term for windward side, the wet side.