Atmosphere & Weather — Set 1
Geography · वायुमंडल और मौसम · Questions 1–10 of 60
Which is the lowest layer of the Earth's atmosphere?
Correct Answer: A. Troposphere
• **Troposphere** = the lowest layer of Earth's atmosphere, containing ~75% of the atmosphere's mass and nearly all water vapor. • **75%** — of total atmospheric mass is concentrated in this layer, where all weather phenomena occur. • 💡 Wrong-option analysis: Mesosphere: third layer, coldest, where meteors burn up; Thermosphere: outermost functional layer, very high temperatures; Stratosphere: second layer above troposphere, contains ozone layer.
The Ozone layer, which protects the Earth from harmful UV rays, is located in which layer?
Correct Answer: C. Stratosphere
• **Stratosphere** = the atmospheric layer 12-50 km above Earth's surface where the ozone layer is located, absorbing most of the sun's UV radiation. • **12-50 km** — the altitude range of the stratosphere, lying immediately above the troposphere. • 💡 Wrong-option analysis: Mesosphere: above stratosphere, where meteors burn; Ionosphere: overlaps mesosphere/thermosphere, reflects radio waves; Troposphere: lowest layer, contains weather but no ozone layer.
In which atmospheric layer do most meteors burn up upon entering the Earth's atmosphere?
Correct Answer: B. Mesosphere
• **Mesosphere** = the atmospheric layer above the stratosphere where most meteors burn up due to friction with gas particles. • **-90°C** — the extreme minimum temperature in the mesosphere, making it the coldest layer of the atmosphere. • 💡 Wrong-option analysis: Troposphere: lowest layer, weather occurs here; Exosphere: outermost layer, where satellites orbit; Stratosphere: ozone layer resides here, below mesosphere.
Which atmospheric layer reflects radio waves back to Earth, facilitating wireless communication?
Correct Answer: A. Ionosphere
• **Ionosphere** = the atmospheric layer containing electrically charged particles (ions) that reflect radio waves back to Earth's surface. • **Ions** — electrically charged particles in this layer overlap with the mesosphere and thermosphere, enabling long-distance wireless communication. • 💡 Wrong-option analysis: Mesosphere: coldest layer, meteors burn here; Stratosphere: ozone layer here, no ion activity; Troposphere: lowest layer, weather phenomena occur here.
What is the phenomenon where temperature increases with altitude instead of decreasing?
Correct Answer: B. Temperature Inversion
• **Temperature Inversion** = a weather phenomenon where a warm air layer settles over cold air near the ground, reversing the normal temperature-altitude relationship. • **Normal lapse rate reversal** — instead of cooling with altitude, temperature rises, trapping pollutants and causing fog and smog. • 💡 Wrong-option analysis: Lapse Rate: the normal decrease of temperature with altitude; Heat Budget: balance between incoming solar and outgoing terrestrial energy; Albedo: reflectivity of a surface.
The term 'Albedo' refers to which property of a surface?
Correct Answer: B. Reflectivity
• **Albedo (Reflectivity)** = the ratio of reflected solar radiation to total incoming solar radiation, measuring how much light a surface reflects. • **Fresh snow** — has very high albedo (close to 1.0), while dark soil has very low albedo, absorbing more heat. • 💡 Wrong-option analysis: Conductivity: ability of a surface to conduct heat or electricity; Humidity: water vapor content in air, not a surface property; Absorptivity: opposite of reflectivity, measures heat absorption.
Which concept explains the balance between incoming solar energy and outgoing terrestrial energy?
Correct Answer: A. Heat Budget
• **Heat Budget** = the balance between incoming solar insolation and outgoing terrestrial radiation that maintains Earth's average temperature. • **Earth's average temperature** — is maintained by this equilibrium; if disturbed, Earth would progressively heat or cool. • 💡 Wrong-option analysis: Greenhouse Effect: trapping of heat by atmospheric gases, a component of heat budget; Solar Constant: rate of solar energy reaching Earth (~1361 W/m²); Global Warming: result of disturbed heat budget, not the concept itself.
Which instrument is primarily used to measure wind speed?
Correct Answer: B. Anemometer
• **Anemometer** = the instrument used to measure wind speed, consisting of rotating cups that spin faster as wind speed increases. • **Wind direction** — is measured separately by a wind vane, not the anemometer. • 💡 Wrong-option analysis: Hygrometer: measures relative humidity; Thermometer: measures temperature; Barometer: measures atmospheric pressure.
The 'Doldrums' is a low-pressure area located around which latitude?
Correct Answer: C. Equatorial region (5°N to 5°S)
• **Doldrums (ITCZ)** = a low-pressure belt in the equatorial region between 5°N and 5°S, also called the Inter-Tropical Convergence Zone, characterized by calm winds. • **5°N to 5°S** — the latitude band where trade winds from both hemispheres converge, creating ascending air currents and low pressure. • 💡 Wrong-option analysis: Polar region: high pressure, polar easterlies; Subtropical region (30°): Horse Latitudes, high pressure belt; Subpolar region (60°): low pressure, source of westerlies.
The 'Horse Latitudes' are associated with which pressure belt?
Correct Answer: B. Subtropical High
• **Subtropical High (Horse Latitudes)** = the high-pressure belt found around 30°-35° latitudes, known for calm winds and little precipitation. • **30°-35° latitude** — where descending air creates high pressure, making these regions dry and calm; historically sailors threw horses overboard to conserve water. • 💡 Wrong-option analysis: Equatorial Low: Doldrums area, rising air and rain; Subpolar Low: around 60°, source of frontal weather; Polar High: near poles, extremely cold and dry.