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Chapter: Atmospheric Circulation and Weather Systems 1-Mark Questions Q1: What is atmospheric pressure? A: Atmospheric pressure is the force exerted by the weight of air on a unit area of the Earth’s surface. Q2: Name the instrument used to measure atmospheric pressure. A: Barometer. Q3: What is a jet stream? A: Jet streams are fast-flowing, narrow air currents in the upper atmosphere, typically located near the tropopause. Q4: Define Coriolis force. A: The Coriolis force is the apparent deflection of moving objects, including wind, due to Earth’s rotation. Q5: Name the three major types of wind systems. A: Trade winds, westerlies, and polar easterlies. Q6: What is the intertropical convergence zone (ITCZ)? A: ITCZ is a low-pressure zone near the equator where trade winds from both hemispheres converge. Q7: What are polar easterlies? A: Polar easterlies are cold, dry winds that blow from high-pressure areas at the poles towards subpolar low-pressure belts. Q8: What is the significance of the Intertropical Convergence Zone (ITCZ)? A: ITCZ is a zone of convergence where trade winds meet, leading to rising air, cloud formation, and heavy rainfall, often influencing tropical climates. Q9: Define doldrums. A: Doldrums refer to the low-pressure, calm region near the equator characterized by little or no wind. Q10: Name the two types of jet streams. A: Subtropical jet streams and polar jet streams..

Q11: What is meant by "horse latitudes"? A: Horse latitudes are subtropical high-pressure zones (around 30°N and 30°S), characterized by calm winds and clear skies. Q12: Which type of cyclone is common in India during monsoons? A: Tropical cyclones. Q13: What is the full form of ITCZ? A: Intertropical Convergence Zone. Q14: Which branch of the monsoon causes rainfall in India? A: The southwest monsoon branch. Q15: Name the two branches of the southwest monsoon in India. A: The Arabian Sea branch and the Bay of Bengal branch. Q16: What is the main cause of the Indian monsoon? A: Differential heating of land and water. Q17: During which months does the southwest monsoon occur in India? A: June to September 2-Mark Questions Q1: Why does wind blow from high-pressure to low-pressure areas? A: Wind blows from high-pressure to low-pressure areas due to the pressure gradient force, which drives air to equalize pressure differences. Q2: What are westerlies, and where are they found? A: Westerlies are prevailing winds that blow from west to east in the mid-latitudes (30°–60°). They are more pronounced in the Southern Hemisphere. Q3:Explain the role of the Coriolis force in atmospheric circulation. A: The Coriolis force causes winds to deflect to the right in the Northern Hemisphere and to the left in the Southern Hemisphere, influencing global wind patterns and ocean currents. Q4: What is a cyclone, and how is it different from an anticyclone? A:Cyclone: A low-pressure system with winds converging towards.

the center, rotating counterclockwise in the Northern Hemisphere. •Anticyclone: A high-pressure system with winds diverging outward, rotating clockwise in the Northern Hemisphere. Q5:Why does the equator have low pressure? A: The equator experiences intense solar heating, causing warm air to rise, resulting in low pressure. Q6:Explain the pressure gradient force. A: The pressure gradient force drives air from areas of high pressure to low pressure. Its strength depends on the difference in pr sure and the distance betwee. the areas. 3-Mark Questions Q1: Describe the tri-cellular model of atmospheric circulation. A: The tri-cellular model divides the Earth’s atmospheric circulation into three cells per hemisphere: 1. Hadley Cell: Circulation near the equator where warm air rises and moves poleward, cooling and descending around 30° latitude. 2. Ferrel Cell: Located between 30° and 60° latitude, with air circulation influenced by the adjacent Hadley and Polar Cells. 3. Polar Cell: Found near the poles, where cold air descends and moves towards lower latitudes. Q2: What is the significance of jet streams? A:1. Jet streams influence weather systems by steering storms and fronts. 2. They impact aviation, as flights use or avoid jet streams to save time and fuel. 3. They contribute to the formation of cyclones and anticyclones. Q3: How do land and sea breezes occur? A:• Daytime (Sea Breeze): Land heats up faster than water, creating low pressure over land. Cool air from the sea moves to replace it..

• Nighttime (Land Breeze): Land cools faster than water, creating high pressure over land. Cool air moves from land to sea. Q4: Differentiate between tropical and temperate cyclones. A: 1. Tropical Cyclones: Form in tropical regions, powered by warm ocean waters, and are smaller in size but more intense. 2. Temperate Cyclones: Form in mid-latitudes, involve frontal systems, and cover a larger area with moderate intensity. Q5: How do jet streams influence weather? A: Jet streams steer weather systems, such as cyclones and anticyclones, and affect temperature patterns, precipitation, and storm formation. 5-Mark Questions Q1:Explain the global pressure belts and their significance. A: Global Pressure Belts: 1. Equatorial Low-Pressure Belt (ITCZ): Located at the equator due to intense solar heating, causing warm air to rise. 2. Subtropical High-Pressure Belt: Found at 30° latitude in both hemispheres due to the descending air of the Hadley Cell. 3. Subpolar Low-Pressure Belt: Located at 60° latitude, where warm westerlies and cold polar easterlies converge. 4. Polar High-Pressure Belt: Found at the poles due to the descending cold air. Significance: 1. Pressure belts drive global wind systems like trade winds, westerlies, and easterlies. 2. They influence weather patterns and precipitation..

3. They play a role in the movement of ocean currents. Q2:Discuss the formation and types of cyclones. A: Formation of Cyclones: Cyclones form due to low-pressure systems, where warm, moist air rises and cools, causing condensation and releasing latent heat. This creates a spiraling system due to the Coriolis force. Types of Cyclones: 1. Tropical Cyclones: • Found in tropical regions (e.g., hurricanes, typhoons). • Form over warm ocean waters (26°C or higher). • Characterized by high winds and heavy rainfall. 2. Temperate Cyclones: • Found in mid-latitudes (30°–60°). • Form due to the interaction of cold and warm air masses. • Associated with frontal systems. Significance: Cyclones influence weather, agriculture, and can cause severe damage to life and property. Q3: Describe the factors affecting the movement of wind. A:1.Pressure Gradient Force: Winds move from high-pressure to low-pressure areas. 2.Coriolis Force: Deflects winds to the right in the Northern Hemisphere and left in the Southern Hemisphere. 3.Frictional Force: Slows down wind movement near the Earth’s surface. 4.Temperature Differences: Create pressure variations that drive winds. 5.Centrifugal Force: Impacts wind direction around curved paths, such as in cyclones and anticyclones. Q4: What are the different types of rainfall? Explain with diagrams. A:1.Convectional Rainfall: • Caused by intense heating of the Earth’s surface..

• Warm air rises, cools, and condenses, leading to rainfall. • Common in equatorial regions. 2.Orographic Rainfall: • Occurs when moist air is forced to rise over a mountain. • The windward side receives rain, while the leeward side remains dry. 3.Frontal Rainfall: • Caused by the interaction of warm and cold air masses. • Warm air rises over the cold air, leading to condensation and rain. (Diagrams should illustrate convection, orographic, and frontal rainfall.) draw the diagram feom the book. Q5: Explain the mechanism of monsoon A.The monsoon is a seasonal reversal of wind patterns, primarily caused by differential heating of land and water. Here's how it works: 1. Differential Heating: During summer, the Indian subcontinent heats up more quickly than the surrounding oceans, creating a low-pressure zone over land and a high-pressure zone over the Indian Ocean. 2. ITCZ Shift: The Intertropical Convergence Zone (ITCZ) shifts northward towards the Indian subcontinent, acting as a zone of convergence for trade winds. 3. Southwest Monsoon Winds: Winds from the Indian Ocean are deflected to the right due to the Coriolis force, becoming southwest monsoon winds. These winds are moisture-laden and bring heavy rainfall to the region. 4. Winter Monsoon: In winter, the process reverses. Land cools faster than the ocean, creating high pressure over the subcontinent and low pressure over the ocean. This generates dry northeast monson winds.subcontinent and low pressure over the ocean. This generates dry northeast monsoon winds..

Key Factors: Differential heating and cooling of land and water. Northward movement of the ITCZ. Role of the Himalayas in blocking cold winds. The Coriolis force influencing wind direction..