Maharashtra Board Class 7 Geography Chapter 4 Air Pressure Solutions

1. Give reasons:

Question 1. Air pressure decreases with increasing altitude.
Answer:

• The proportion of dust in the air, water vapour, heavy gases, etc. is higher in the air and closer to the surface of the earth.
• This proportion decreases with increasing altitude.
• As one moves higher and higher from the surface of the earth, the air becomes thinner and thinner.
• As a result, the air pressure decreases with increasing altitude.

In simple words: Air pressure drops as you go higher because the air gets thinner and there's less of it pushing down from above.

🎯 Exam Tip: Understanding the inverse relationship between altitude and air pressure is fundamental for explaining atmospheric phenomena.

Question 2. Pressure belts oscillate.
Answer:

• The duration and the intensity of sunrays varies during particular periods of the year in both the hemispheres.
• So, the locations of the temperature zones and the pressure belts dependent on the sun's heat also vary.
• This change is of the order of 5° to 7° towards the north in Uttarayan1 and 5° to 7° south in Dakshinayan2.
• In this way pressure belts oscillate.

In simple words: Pressure belts shift with the seasons because the intensity and position of the sun's rays change, causing temperature zones and the dependent pressure belts to move.

🎯 Exam Tip: Remember that the oscillation of pressure belts is a direct consequence of the Earth's tilt and revolution, influencing global climate patterns.

2. Give short answers to the following questions.

Question 1. What effect does temperature have on air pressure?
Answer:

• Temperature and air pressure are closely related. Wherever the temperature is high, the air pressure is low.
• As the temperature rises, the air gets heated, expands, and becomes lighter.
• This lighter air in the vicinity of the earth's surface starts moving up towards the sky
• As a result, the air pressure in such areas decreases.

In simple words: High temperatures cause air to expand, become lighter, and rise, leading to lower air pressure; conversely, low temperatures result in higher air pressure.

🎯 Exam Tip: This inverse relationship between temperature and air pressure is a core concept in meteorology and explains many weather phenomena.

Question 2. Why is the subpolar low pressure belt formed?
Answer:

• Due to earth's curvature, the area between two parallels gets reduced as we move towards the poles.
• This results in lesser friction1 of the air with the earth's surface.
• Air in this region is thrown out because of this reduced friction and also because of the earth's rotational motion.
• This leads to the development of a low pressure belt in the sub polar region i.e. in area between 55° & 65° parallels in both the hemispheres.

In simple words: The subpolar low pressure belt forms because the Earth's rotation and reduced friction at higher latitudes cause air to be thrown outwards, leading to lower pressure between 55° and 65° parallels.

🎯 Exam Tip: The formation of the subpolar low pressure belt is a dynamic process influenced by both Earth's shape and rotation, not just temperature.

3. Write notes on:

Question 1. Mid-latitudinal high pressure belts.
Answer:

• The heated air from the equatorial region becomes lighter, starts ascending and after reaching higher altitudes, moves towards the polar region, i.e., towards the North and the South Pole.
• Due to low temperatures at the higher altitudes, the air cools down and becomes heavier.
• This heavier air descends down in both the hemispheres in the region between 25° to 35° parallels.
• This leads to the formation of high pressures, belts in these parallels of latitudes in both the hemispheres.
• This air is dry, hence the region does not get rainfall.
• Consequently, most of the hot deserts on the earth are found in these regions.

In simple words: Mid-latitudinal high pressure belts form when warm, rising air from the equator cools at higher altitudes and descends between 25° to 35° parallels, creating dry conditions and deserts.

🎯 Exam Tip: Connect the descending dry air in these belts to the prevalence of hot deserts in these latitudes, a key geographical concept.

Question 2. Horizontal distribution of air pressure.
Answer:

• The heat received from the sun is uneven in different regions.
• The distribution of temperature is uneven from the equator to the poles.
• This difference can lead to difference in air pressure.
• There are four air pressure belts formed on the earth surface.
• Equatorial low-pressure belt between 5°N and 5°S parallels as the temperature is high here.
• Mid latitudinal high-pressure belt between 25° and 35° parallels due to descending heavier air.
• Subpolar low-pressure belt formed between 55° and 65° parallels due to friction and rotation.
• Polar high-pressure belt formed between 80° and 90° parallels due to low temperatures.

In simple words: Air pressure varies horizontally across the Earth due to uneven solar heating, creating distinct high and low pressure belts at different latitudes.

🎯 Exam Tip: Be able to name and locate the four major air pressure belts and their primary causes (temperature or dynamic factors).

4. Fill in the gaps with the appropriate option.

Question 1. At higher altitudes air becomes ____ (thicker, thinner, hotter, more humid)
Answer: thinner
In simple words: As you go higher up, the air becomes less dense and lighter.

🎯 Exam Tip: This is a direct consequence of gravity and atmospheric composition; thinner air means less oxygen and lower pressure.

Question 2. Air pressure is expressed in ____.(millibars, millimeters, milliliters, milligrams)
Answer: millibars
In simple words: Air pressure is typically measured in units called millibars, which indicate the force exerted by the atmosphere.

🎯 Exam Tip: Knowing the correct units for measuring atmospheric elements like pressure (millibars) is important for scientific accuracy.

Question 3. On the earth, air pressure is ____ (uniform, uneven, high, low)
Answer: uneven
In simple words: Air pressure varies significantly across the Earth's surface due to factors like temperature, altitude, and rotation.

🎯 Exam Tip: Recognize that uneven air pressure is the driving force behind wind and other atmospheric movements.

Question 4. The ____ pressure belt spreads between 5° North and 5° South parallel. (equatorial low, polar high, subpolar low, mid-latitudinal high)
Answer: equatorial low
In simple words: The region around the equator, between 5° North and 5° South, experiences low air pressure due to high temperatures.

🎯 Exam Tip: Accurately identifying the location and type of each pressure belt is essential for understanding global circulation patterns.

Question 5. How does a high-pressure belt get formed near 30° parallel? Why does this region have hot deserts?
Answer: (i) The heated air from the equatorial region becomes lighter, starts ascending and after reaching higher altitudes, moves towards the polar region, i.e., towards the North and the South Pole. (ii) Due to low temperatures at the higher altitudes, the air cools down and becomes heavier. This heavier air descends down in both the hemispheres in the region between 25° to 35° parallels. (iii) This leads to the formation of high pressures belts in these parallels of latitudes in both the hemispheres. (iv) This air is dry, hence the region does not get rainfall. Consequently, most of the hot deserts on the earth are found in these regions.
In simple words: Air heated at the equator rises, moves poleward, then cools and descends around 30° latitude, creating a high-pressure belt with dry conditions, which is why hot deserts form there.

🎯 Exam Tip: Understand the Hadley Cell circulation model to fully grasp how air movement from the equator leads to these high-pressure zones and arid climates.

Question 6. Draw a neat diagram showing pressure belts. Label the diagram.
Answer:
ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र पृथ्वी पर विभिन्न वायुदाब पेटियों और ग्रहीय पवनों को दर्शाता है। इसमें ध्रुवीय उच्च दाब पेटी, उपध्रुवीय निम्न दाब पेटी, मध्य-अक्षांशीय उच्च दाब पेटी और भूमध्यरेखीय निम्न दाब पेटी को विशिष्ट अक्षांशों (जैसे 5°, 25°, 35°, 55°, 65°) पर ध्रुवीय पवनों, पछुआ पवनों और व्यापारिक पवनों की दिशाओं के साथ दिखाया गया है।
In simple words: The diagram illustrates the Earth's major pressure belts—equatorial low, mid-latitude high, subpolar low, and polar high—along with their associated planetary winds.

🎯 Exam Tip: Practice drawing and accurately labeling all the major pressure belts and global wind patterns, including their approximate latitudinal extents, as this is a common and important exam question.

Formative Assessment

Can you tell?

Observe the diagram Fig. (a) and (b) carefully and answer the following questions:

ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र पृथ्वी के तापमान क्षेत्रों को दर्शाता है। इसमें ध्रुवों के पास शीत कटिबंध, मध्य-अक्षांशों में शीतोष्ण कटिबंध और भूमध्य रेखा के पास उष्ण कटिबंध को 90°N/S, 66°30′N/S, 23°30′N/S और 0° (भूमध्य रेखा) जैसे अक्षांशों के साथ प्रदर्शित किया गया है।
ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र पृथ्वी पर विभिन्न वायुदाब पेटियों और ग्रहीय पवनों को दर्शाता है। इसमें ध्रुवीय उच्च दाब पेटी, उपध्रुवीय निम्न दाब पेटी, मध्य-अक्षांशीय उच्च दाब पेटी और भूमध्यरेखीय निम्न दाब पेटी को विशिष्ट अक्षांशों (जैसे 5°, 25°, 35°, 55°, 65°) पर ध्रुवीय पवनों, पछुआ पवनों और व्यापारिक पवनों की दिशाओं के साथ दिखाया गया है।

Question 1. Which pressure belt is mainly found in the Tropics?
Answer: Equatorial low pressure belt is mainly found in the tropics.
In simple words: The low pressure belt located around the equator is the main one found in the tropical regions.

🎯 Exam Tip: Associate the Tropics (between the Tropics of Cancer and Capricorn) with the Equatorial Low Pressure Belt, driven by intense solar heating.

Question 2. With which pressure belt are the polar winds associated? In which temperature zone are they observed?
Answer: The polar winds are associated with polar high pressure belt and sub polar low pressure belt. It is observed in the frigid zone.
In simple words: Polar winds are linked to the polar high pressure and subpolar low pressure belts and are typically found in the frigid (polar) temperature zones.

🎯 Exam Tip: Remember that polar winds originate from the high pressure at the poles and are found in the coldest temperature zones, the frigid zones.

Question 3. What could be the reason behind a low pressure belt in the Tropics?
Answer: Low pressure belt is formed in the tropics because the temperature is high.
In simple words: High temperatures in the tropical region cause the air to heat up, expand, and rise, resulting in a low pressure belt.

🎯 Exam Tip: Always link high temperatures with low pressure, especially in the context of the equatorial region, due to the air's expansion and ascent.

Question 4. With which pressure belts are the winds in the Temperate zone associated?
Answer: The winds in temperate zone are associated with mid latitudinal high pressure belt.
In simple words: Winds within the temperate zones are connected to the mid-latitudinal high pressure belts, influencing their direction and characteristics.

🎯 Exam Tip: Understand that the Westerlies, prominent in the temperate zones, are influenced by the mid-latitudinal high pressure belts.

Question 5. Write the latitudinal extent of the low pressure belts.
Answer: The latitudinal extent of Equatorial low pressure belt is between 50°N & 50°S parallel & the latitudinal extent of the sub polar low pressure belt is between 55° & 65° parallel in both the hemispheres.
In simple words: The low pressure belts are found around the equator (0°-5° N/S) and in the subpolar regions (55°-65° N/S) in both hemispheres.

🎯 Exam Tip: Memorize the approximate latitudinal ranges for all pressure belts, especially the low pressure ones, as they are crucial for global circulation understanding.

Observe the map given above and study the distribution of air pressure and answer the following

ℹ️ चित्र व्याख्या (Diagram Explanation): यह मानचित्र विश्व में वार्षिक औसत वायुदाब (मिलीबार में) के वितरण को दर्शाता है। इसमें समदाब रेखाओं (समान दाब वाली रेखाएं) और उनके मूल्यों (जैसे 1013, 1009 मिलीबार) का उपयोग करके महाद्वीपों और महासागरों में उच्च और निम्न दाब क्षेत्रों को वैश्विक स्तर पर चित्रित किया गया है।

Question 1. The nature of the isobars.
Answer: The isobars are joining places of equal air pressure on the map.
In simple words: Isobars are lines on a map that connect locations having the same atmospheric pressure.

🎯 Exam Tip: Know the definition of an isobar; understanding its purpose is key to interpreting weather maps and pressure distribution.

Question 2. High and low pressure belts and their latitudinal position.
Answer: (i) The latitudinal position of high pressure belt is between 25° & 35° parallels and between 80° & 90° parallels in both the hemisphere (ii) The latitudinal position of low pressure belt is between 0° & 5° parallels and between 55° & 65° parallels in both the hemispheres.
In simple words: High pressure belts are located around 25°-35° and 80°-90° latitude, while low pressure belts are found near the equator (0°-5°) and subpolar regions (55°-65°).

🎯 Exam Tip: Be precise with the latitudinal ranges for both high and low pressure belts, as this detail is often assessed in exams.

Question 3. The direction of the isobars and the distance between successive isobars over the oceans and continents.
Answer: (i) In the northern hemisphere most of the isobars are in southwest to north east direction over the continents. Also the distance between the isobars varies. (ii) Closely spaced isobars indicate large pressure changes over a small area. Widely spaced isobars indicate gentle or gradual pressure change. (iii) In the southern hemisphere, the isobars extend in east-west direction. The distance between the isobars is fairly constant over the oceans & so the isobars are fairly parallel to each other.
In simple words: Isobars show varying directions and spacing over continents due to land-sea differences, but tend to be more uniform and parallel over oceans, especially in the Southern Hemisphere.

🎯 Exam Tip: The spacing of isobars indicates wind strength (closely spaced = strong winds), and their direction reveals the general pattern of pressure systems.

Question 4. Comparison of the isobars in the northern and the southern hemispheres.
Answer: In the northern hemisphere the isobars are far spaced and uneven, whereas in the southern hemispheres it is closely spaced and parallel.
In simple words: Northern Hemisphere isobars are irregular and spread out due to landmass distribution, while Southern Hemisphere isobars are more consistent and parallel because of the larger ocean expanses.

🎯 Exam Tip: Understand that the greater landmass in the Northern Hemisphere causes more varied pressure patterns compared to the predominantly oceanic Southern Hemisphere.

Use your brainpower !

Question 1. If there is low pressure at the equator, what will be the condition of air pressure in the Arctic Zone?
Answer: The Arctic zone will experience high pressure as the temperature is lower than 0°C.
In simple words: If the equator has low pressure due to heat, the cold Arctic zone will have high pressure because cold air is denser and sinks.

🎯 Exam Tip: Remember the general principle: cold regions usually have high pressure, and warm regions have low pressure, due to air density differences.

Try this:

Question 1.

• Take a flying lantern.
• Tie an approximately 5m long thread to the flying lantern so that you can bring the lantern down whenever required.
• After carefully reading the instructions given on the package of the lantern open it and light the candle placed in it.
• After some time, bring the lantern down with the help of the thread and put off the candle.

In simple words: This activity demonstrates how heated air becomes lighter and rises, creating lift, similar to how air pressure changes affect weather.

🎯 Exam Tip: Pay attention to how simple experiments can illustrate fundamental scientific principles like air density and buoyancy, which are key to understanding air pressure.

Question 2. Did the flying lantern start ascending immediately after the candle was lit?
Answer: Yes
In simple words: The lantern started rising right away because the heated air inside it immediately became lighter than the surrounding cool air.

🎯 Exam Tip: This prompt checks understanding of the basic principle of convection: hot air rises due to its lower density.

Question 2. What would have happened to the flying lantern had the candle got extinguished after the lantern had gone up in the air?
Answer: The lantern would have fallen back on the earth.
In simple words: If the candle went out, the air inside the lantern would cool, become heavy, and cause the lantern to descend back to the ground.

🎯 Exam Tip: This question tests your grasp of the cause-and-effect relationship between heat, air density, and buoyancy.

Give it a try:

Question 1. Study the temperative distribution map given in your std VI textbook and the pressure distribution map in this lesson to find the correlation between air temperature and air pressure.
Answer:

• The temperature deceases continuously from the equator to the poles but the air pressure varies alternately.
• In the equatorial region the average temperature is high. Hence, the air pressure is low.
• In the polar regions, the temperature is low & hence the air pressure is comparative high.

In simple words: This exercise helps you see how changes in air temperature across the globe are directly linked to the formation of different air pressure zones.

🎯 Exam Tip: Understanding the inverse relationship between temperature and air pressure is crucial for explaining global wind patterns and climate zones.

Fill in the blanks choosing the correct option from the bracket:

Question 1. Pressure belts oscillates between ____ parallels. (5° to 7°, 10° to 20°, 80° and 90°, 25° to 30°)
Answer: 5° to 7°
In simple words: The Earth's pressure belts shift by a small degree (5° to 7°) seasonally, following the sun's apparent movement.

🎯 Exam Tip: Remember the specific range of oscillation for pressure belts as it indicates the extent of seasonal shifts.

Question 2. The instrument used to measure air pressure is ____.(barometer, thermometer, hygrometer, seismometer)
Answer: barometer
In simple words: A barometer is the tool specifically designed to measure atmospheric pressure.

🎯 Exam Tip: Be familiar with common meteorological instruments and what they measure.

Question 3. In both the polar regions, the temperature is below ____ throughout the year. (5°C, 0°C, 7°C, 6°C)
Answer: 0°C
In simple words: Temperatures in both polar regions consistently stay below freezing point (0°C) all year round.

🎯 Exam Tip: This fact highlights the extreme cold of polar regions, which directly contributes to the formation of high pressure systems there.

Question 4. The line that joins the places of equal pressure on the map is called an ____. (isotherm, isohytes, millibars, isobar)
Answer: isobar
In simple words: An isobar is a line on a map that connects points where the atmospheric pressure is the same.

🎯 Exam Tip: Knowing the term 'isobar' is essential for interpreting weather maps and understanding pressure gradients.

Match the following:

Question 1.

Answer: 1-c 2-a 3-d 4-b
In simple words: This match-the-following connects each major pressure belt to its corresponding latitudinal range on Earth.

🎯 Exam Tip: Ensure you can accurately pair each pressure belt with its correct latitudinal position, as this fundamental knowledge is often tested.

Fill in the blanks:

Question 1. The latitudinal extent of the temperate zones is much ____ while belts are narrower.
Answer: Larger
In simple words: Temperate zones cover a broad range of latitudes, unlike pressure belts which are relatively confined.

🎯 Exam Tip: Distinguish between the broadness of temperature zones and the narrowness of pressure belts in terms of latitudinal extent.

Question 2. The extent of air pressure belt is upto ____ parallel.
Answer: 10°
In simple words: Air pressure belts typically extend up to about 10 degrees of latitude in width.

🎯 Exam Tip: Remember that pressure belts are relatively narrow bands, generally spanning about 10 degrees of latitude.

Question 3. Pressure belts are formed between the ____ and the pole.
Answer: Equator
In simple words: Pressure belts are found distributed across the globe, originating between the equator and extending towards the poles.

🎯 Exam Tip: Understand that the global pressure system is organized from the equator outward to the poles.

Question 4. The sun rays fall perpendicular between the ____and____.
Answer: Tropic of Cancer, Tropic of Capricorn
In simple words: The sun's most direct rays, falling perpendicularly, are concentrated in the region between the Tropic of Cancer and the Tropic of Capricorn.

🎯 Exam Tip: This defines the tropical zone, where direct solar insulation leads to high temperatures and the equatorial low pressure belt.

Question 5. Due to the earths curvature, the area betweentwo parallels gets ____ as we move towards the poles.
Answer: reduced
In simple words: As one moves from the equator towards the poles, the Earth's curvature causes the distance between lines of latitude to appear to narrow.

🎯 Exam Tip: This concept explains why areas near the poles appear 'smaller' on flat maps and influences atmospheric dynamics.

Question 6. The air pressure at sea level is ____ millibars.
Answer: 1013.2
In simple words: The average atmospheric pressure at sea level is approximately 1013.2 millibars.

🎯 Exam Tip: Know the standard atmospheric pressure at sea level as a baseline for understanding pressure variations.

State whether the following statements are true or false:

Question 1. Air pressure is uniform on all places on the earth's surface.
Answer: false
In simple words: Air pressure is not the same everywhere on Earth; it varies due to altitude, temperature, and other factors.

🎯 Exam Tip: This statement tests your fundamental understanding of air pressure distribution, which is inherently uneven.

Question 2. Whenever the temperature is high, the air pressure is also high.
Answer: false
In simple words: High temperatures typically lead to low air pressure because warm air expands and rises.

🎯 Exam Tip: Remember the inverse relationship between temperature and air pressure: high temperature means low pressure, and vice versa.

Question 3. The heat received from the sun, is uneven in different regions.
Answer: true
In simple words: Different parts of the Earth receive varying amounts of solar energy due to factors like latitude, angle of incidence, and atmospheric conditions.

🎯 Exam Tip: This uneven heating is the primary driver of global temperature and pressure differences, leading to weather and climate patterns.

Question 4. In both the polar regions, the temperature is low throughout the year.
Answer: true
In simple words: Polar regions consistently experience very low temperatures year-round due to the oblique angle of the sun's rays.

🎯 Exam Tip: This constant cold contributes to the formation of stable high-pressure systems at the poles.

Question 5. Air pressure is measured in units of millimetres.
Answer: false
In simple words: Air pressure is measured in millibars or hectopascals, not millimetres, which are a unit of length.

🎯 Exam Tip: Always use the correct scientific units; millibars are standard for air pressure, although inches of mercury or mmHg were historically used.

Answer the following questions in one to two sentence:

Question 1. Which factors influence air pressure?
Answer: The altitude of a region, temperature of the air and the amount of water vapour in the air are some factors influencing air pressure.
In simple words: Air pressure is affected by a region's height above sea level, the air's temperature, and how much moisture (water vapor) it contains.

🎯 Exam Tip: Remember these three key factors-altitude, temperature, and water vapor-as they collectively determine local and global air pressure variations.

Question 2. What is the extent of air pressure belt?
Answer: The extent of air pressure belt is generally upto 10° parallel.
In simple words: An air pressure belt typically spans a latitudinal range of about 10 degrees.

🎯 Exam Tip: This indicates that pressure belts are relatively narrow bands of pressure around the Earth.

Question 3. What is the latitudinal extent of temperate zone?
Answer: The latitudinal extent of temperate zone is from 23°30′N to 66°30′N and 23° 30'S to 66° 30'S.
In simple words: The temperate zones are located between the Tropics and the Polar Circles, specifically from 23°30′ to 66°30′ in both the Northern and Southern Hemispheres.

🎯 Exam Tip: Clearly distinguish between the latitudinal extents of temperature zones and pressure belts; temperature zones are much broader.

Question 4. What is the temperature in the polar region?
Answer: In both the polar regions, the temperature is below 0°C throughout the year.
In simple words: Polar regions consistently experience temperatures below freezing (0°C) all year because they receive very little direct sunlight.

🎯 Exam Tip: This low temperature is a key characteristic of polar regions and directly influences their high-pressure systems.

Question 5. Why do all things in and on the earth stay earth bound?
Answer: All things in and on the earth stay bound due to the earth's gravity.
In simple words: Everything on Earth, including air and objects, is held down by the force of Earth's gravity.

🎯 Exam Tip: Gravity is the fundamental force responsible for keeping both objects and the atmosphere attached to the Earth's surface.

Question 6. Why are temperature zones created on the surface of the earth?
Answer: The heat received from the sun is uneven in different regions. Hence the distribution of the temperature is uneven from the equator to the poles. As a result, temperature zones are created.
In simple words: Temperature zones exist because the Earth's spherical shape causes sunlight to hit different areas at varying angles, leading to an uneven distribution of heat from the equator to the poles.

🎯 Exam Tip: The Earth's tilt and curvature, leading to uneven solar radiation, are the primary reasons for the formation of distinct temperature zones.

Question 7. Most of the hot deserts on the earth are found in which region?
Answer: Most of the hot deserts on the earth are found in the mid latitudinal high pressure belt ie; between 25°- 30° parallels in both hemispheres.
In simple words: Most hot deserts are located in the mid-latitude high-pressure belts, specifically between 25° and 30° latitude in both hemispheres, where dry air descends.

🎯 Exam Tip: Connect the mid-latitude high-pressure belts (horse latitudes) with the descending dry air that prevents rainfall, thus creating deserts.

Give reasons:

Question 1. Air pressure is maximum at sea level.
Answer:

• All things in and on the earth stay earthbound because of the earth's gravity. This includes air which is in the gaseous form.
• Due to the earth's gravity, air is pulled to the earth's surface.
• Also as one moves higher & higher from the earth's surface the air becomes thinner & thinner.
• Therefore, the air pressure is maximum at sea- level.

In simple words: Air pressure is highest at sea level because the entire weight of the atmosphere above it is pulled down by gravity, making the air densest at the lowest altitude.

🎯 Exam Tip: This is a fundamental concept: air pressure decreases with altitude because there's less atmospheric mass above you.

Question 2. A low pressure belt is formed near the equator.
Answer:

• The sunrays can be perpendicular between the Tropic of Cancer and the Tropic of Capricorn.
• The temperature is higher in this region.
• Hence air in this region gets heated, expands and becomes lighter and moves towards the sky.
• As this process operates continuously, a low pressure belt gets formed in the central part of this region between the parallels 5° N and 5° S, near the equator.

In simple words: The equator receives intense sunrays, heating the air, causing it to expand, become lighter, and rise, thereby creating a persistent low-pressure belt.

🎯 Exam Tip: Always associate the equatorial region with high temperatures, rising air, and low pressure, which drives global atmospheric circulation.

Question 3. High pressure belt is formed near the polar region.
Answer:

• In both the polar regions, the temperature is below 0° throughout the year.
• The air is cold.
• Hence, high pressure belt is formed in the polar region.

In simple words: High pressure belts form near the poles because the consistently very low temperatures cause the air to be cold, dense, and sink.

🎯 Exam Tip: Remember that extreme cold makes air dense and heavy, leading to high pressure at the poles.

Question 4. Low pressure belt is observed between 55° and 65° parallels in both the hemispheres.
Answer:

• Due to the earth's curvature, the area between two parallels gets reduced as we move towards the poles. This results in lesser friction of the air with the earth's surface.
• The air between 55° and 65° parallels is thrown out because of the reduced friction and also due to the earth's rotation.
• Therefore, a low pressure belt is observed between 55° and 65° parallels in both the hemispheres.

In simple words: A low-pressure belt forms between 55° and 65° latitudes due to the Earth's rotation, which causes air to be thrown outwards, reducing friction and pressure.

🎯 Exam Tip: Understand that the subpolar low-pressure belts are primarily dynamic, caused by Earth's rotation, rather than solely thermal in origin.

Question 5. Temperature and air pressure are closely related.
Answer:
• Wherever the temperature is high, the air pressure is low. As the temperature rises the air gets heated, expands, and become lighter.
• Thin, lighter air in the vicinity3 of the earth's surface starts moving up towards the sky. As a result the air pressure in such area decreases.
• Hence, temperature and air pressure are closely related.
In simple words: High temperatures cause air to heat, expand, and become lighter, leading to lower air pressure. Conversely, lower temperatures make air denser and increase air pressure.

🎯 Exam Tip: Students should understand the inverse relationship between temperature and air pressure, as this is a fundamental concept in geography.

Question 6. Most of the hot deserts on the earth are found in mid-latitudinal high pressure belts.
Answer:
• The air in mid-latitudinal high pressure belt (between 25° to 35° parallels in both hemisphere) is found to be dry.
• The amount of water vapour is very low & hence this region gets extremely scarce or no rainfall.
• Consequently, most of the hot deserts on the earth are found in mid latitudinal high pressure belts.
In simple words: Hot deserts typically form in mid-latitudinal high-pressure belts because the air in these regions is dry with very little moisture, resulting in extremely low rainfall.

🎯 Exam Tip: Linking the concept of dry, descending air in high-pressure belts to the formation of deserts is crucial for comprehensive understanding.

Give Short Answers To The Following Questions:

Question 1. What are the effects of air pressure?
Answer: Air pressure has the following effects.
• Origin of winds.
• Generation of storms
• Convectional type of rain.
In simple words: Air pressure differences drive wind movement, which can lead to the formation of storms and influence the type of rainfall, such as convectional rain.

🎯 Exam Tip: Remember these three key effects as direct consequences of varying air pressure for quick recall in exams.

Question 2. What is the difference between the temperature zones and pressure belts?
Answer:
(i) The difference between the temperature zones & pressure belts is that the latitudinal extent of temperature zones is much larger while pressure belts are narrower.
(ii) For example, the Temperate zone extends from 23°30′ to 66°30′ in both hemisphere. Compared to this the pressure belt has limited extent which is generally upto 10° parallel.
(iii) Also the temperature zones are continuous & spread from the equator to the poles from Torrid to Frigid.
(iv) Pressure belts are not continuous & areas of high & low pressure are found in different regions from the equator to the poles.
In simple words: Temperature zones cover large, continuous latitudinal areas from the equator to the poles, while pressure belts are narrower, discontinuous bands of high and low pressure found at different latitudes.

🎯 Exam Tip: Focus on the differences in latitudinal extent and continuity between temperature zones and pressure belts, often a point of confusion for students.

Question 3. How does a high-pressure belt get formed near 30° parallel? Why does this region have hot deserts?
Answer:
(i) The heated air from the equatorial region becomes lighter, starts ascending and after reaching higher altitudes, moves towards the polar region, i.e., towards the North and the South Pole.
(ii) Due to low temperatures at the higher altitudes, the air cools down and becomes heavier. This heavier air descends down in both the hemispheres in the region between 25° to 35° parallels.
(iii) This leads to the formation of high pressures belts in these parallels of latitudes in both the hemispheres.
(iv) This air is dry, hence the region does not get rainfall. Consequently, most of the hot deserts on the earth are found in these regions.
In simple words: Air rising from the equator cools and descends around 30° latitude, creating a high-pressure belt. This descending air is dry, preventing rainfall and leading to the formation of hot deserts in these regions.

🎯 Exam Tip: Understanding the Hadley Cell circulation—rising air at the equator and sinking air at 30° latitude—is key to explaining both the high-pressure belt and the desert formation.

Think About It:

Question 1. What will be the effect on air pressure if the temperature drops? Why?
Answer: If the temperature drops, the air pressure will increase as the air becomes heavy.
In simple words: When temperature drops, air becomes denser and heavier, leading to an increase in air pressure.

🎯 Exam Tip: This question tests the inverse relationship between temperature and air pressure, a fundamental concept. State it clearly and concisely.