Latitude generally reduces temperature away from the equator. Locate each city in an atlas, record its latitude, then obtain the August mean temperature from a reliable weather table. The values above are suitable approximate examples; yearly observations can differ.
Sample completion: Kanniyakumari — about 8.1°N — warm August temperature, usually about 27–29°C; Delhi — about 28.6°N — about 28–31°C; Moscow — about 55.8°N — about 16–20°C. Use an atlas and the selected year’s August weather record for exact observations.
This activity demonstrates the normal lapse-rate idea: temperature generally decreases as altitude increases. Madurai is low-lying and warmer, while Ooty and Shimla are high-altitude hill stations and cooler. Exact monthly temperatures vary by year.
Sample completion: Madurai — about 100 m — May temperature commonly around 30–35°C; Udhagamandalam (Ooty) — about 2,240 m — around 15–20°C; Shimla — about 2,200 m — around 15–22°C. Use the selected year’s May record for exact values.
Trade winds are part of the Hadley cell circulation. Air rises at the equator and descends near 20°–30° latitudes, creating high-pressure, dry subsiding zones. These persistent dry conditions, often combined with cold ocean currents (e.g., Humboldt Current for Atacama), lead to formation of major deserts such as the Sahara and Atacama.
Subtropical descending dry air associated with trade winds produces arid belts near ~20°–30° latitude where deserts like the Sahara and Atacama are found.
The Bay of Bengal has warm waters, favorable pre- and post-monsoon conditions, and steering winds that produce and guide tropical cyclones toward the eastern coast of India. The Coromandel Coast (including Cuddalore and Nagapattinam) is geographically exposed with a shallow continental shelf, making it prone to frequent cyclone landfalls and severe impacts.
They lie on the Coromandel Coast facing the Bay of Bengal where warm sea surface and regional circulation favour frequent cyclogenesis and landfall.
- a. Helium
- b. carbon dioxide
- c. oxygen
- d. methane
Oxygen is essential for respiration in most living organisms and is therefore the most important gas for survival.
c
- a. Troposphere
- b. Stratosphere
- c. Exosphere
- d. Mesosphere
The troposphere is the lowest atmospheric layer where weather and most clouds occur, extending up to about 8–18 km depending on latitude.
a
- a. Exosphere
- b. Ionosphere
- c. Mesosphere
- d. Stratosphere
The ionosphere contains charged particles that reflect and refract radio waves, enabling long-distance radio communication.
b
- a. Precipitation
- b. evaporation
- c. transpiration
- d. condensation.
Condensation is the process where water vapor (gas) turns into liquid water (droplets).
d
- a. Sun
- b. Moon
- c. Stars
- d. Clouds.
The Sun supplies most of the Earth's energy, driving climate, weather and supporting life through photosynthesis.
a
- a. Troposphere
- b. Ionosphere
- c. Mesosphere
- d. Exosphere
All common cloud types form in the troposphere, the atmospheric layer closest to Earth's surface where weather occurs.
a
- a. Alto-cumulus
- b. Alto-Stratus
- c. Nimbo - stratus
- d. Cirro-stratus.
Altocumulus clouds often appear as small, rounded masses resembling a flock of sheep; hence they are called 'sheep clouds'.
a
- a. prevailing winds
- b. periodic winds
- c. local winds
- d. none of the above.
Monsoons are seasonal (periodic) winds that reverse direction between summer and winter, bringing distinct wet and dry seasons.
b
- a. frost
- b. fog
- c. mist
- d. sleet.
Frost is formed when water vapour deposits as ice on surfaces at temperatures below freezing.
a
- a. Pressure
- b. wind
- c. cyclones
- d. snow.
The 'eye' of a cyclone is the central region of low pressure with relatively calm conditions, so 'pressure' (the low-pressure centre) is the best option among those given.
a
- a. Wind
- b. storm
- c. Air current
- d. drift.
An 'air current' is a general term for the movement of air; vertical movements specifically are called updrafts or downdrafts which are types of air currents.
c
Provide a concise definition: the layer of gases (air) surrounding Earth, retained by Earth's gravity, composed primarily of nitrogen (~78%) and oxygen (~21%) with traces of other gases. It protects life, regulates temperature and weather.
The atmosphere is the envelope of gases surrounding the Earth, held by gravity, composed mainly of nitrogen, oxygen and trace gases, and essential for life and climate.
List with brief notes: latitude (controls solar angle and day length), altitude (temperature decreases with height), distance from sea (maritime vs continental climates), ocean currents (warm/cold currents modify coastal climate), prevailing winds, mountain barriers, vegetation cover, and anthropogenic effects.
Main factors: latitude, altitude, distance from the sea (continentality), ocean currents, prevailing winds, relief (topography), vegetation and human activities.
Short note: Lapse rate = temperature change per unit height. Types: environmental lapse rate (actual), dry adiabatic lapse rate (~9.8°C/km for unsaturated air), and moist adiabatic lapse rate (~5–6°C/km for saturated air). It is important in atmospheric stability and cloud formation.
Lapse rate is the rate at which air temperature decreases with increasing altitude; the average environmental lapse rate is about 6.5°C/km.
List: (1) Trade winds — blow from subtropical highs to equator (NE in N. Hemisphere, SE in S. Hemisphere); (2) Westerlies — mid-latitude prevailing winds from the west; (3) Polar easterlies — cold winds blowing from polar highs toward subpolar regions. These are part of the three-cell circulation in each hemisphere.
Main planetary wind systems: Trade Winds (NE and SE trades), Prevailing Westerlies, and Polar Easterlies (associated with Hadley, Ferrel and Polar cells).
a) Trade winds: part of Hadley circulation, blow easterly toward the equator, reliable and persistent. b) Roaring Forties: intense mid-latitude westerlies in the Southern Hemisphere around 40°–50°S; little land to slow them, they are strong and produce stormy conditions on ships' routes.
a) Trade winds: steady winds from subtropical highs to the equator (NE trades in N. Hemisphere, SE trades in S.), used historically for navigation. b) Roaring Forties: strong westerly winds between ~40°–50° S caused by large ocean expanse and pressure gradients, producing rough seas.
Convectional rainfall: Caused by heating of the ground that makes warm air rise, cool and condense (common in tropics and afternoons). Orographic (relief) rainfall: Occurs when moist air is forced to rise over mountains, cools and condenses on windward slopes. Frontal (cyclonic) rainfall: Caused by the meeting of warm and cold air masses along a front; warm air rises over cold air, cools and forms rain (common in temperate regions).
Convectional, Orographic (relief), and Frontal (cyclonic) rainfall.
a. Drizzle — light continuous precipitation of tiny water droplets, reduces visibility. b. Rain — common form of liquid precipitation from nimbostratus or cumulonimbus clouds. c. Sleet — occurs when raindrops freeze before reaching ground or as pellets; common in cold conditions. d. Snow — forms when air temperature is below freezing and water vapour deposits as ice crystals. e. Hail — large, often hard ice lumps formed by repeated uplift in thunderclouds; can damage crops and structures.
a. Drizzle: very fine light liquid droplets (<0.5 mm). b. Rain: liquid precipitation with droplet size >0.5 mm. c. Sleet: frozen raindrops or mixture of rain and ice pellets (freezing rain). d. Snow: ice crystals or flakes formed by direct freezing of water vapour. e. Hail: concentric layers of ice pellets formed in strong cumulonimbus up‑and‑down drafts.
Tropical cyclones: develop over warm tropical oceans, have a warm core and spiral structure; local names include hurricanes (Atlantic), typhoons (NW Pacific), and cyclones (Indian Ocean). Temperate (extratropical) cyclones: form in middle latitudes along fronts between air masses, associated with cold and warm fronts. (Simpler school classification: tropical vs. temperate.)
Cyclones are classified mainly as Tropical cyclones and Temperate (extratropical) cyclones; tropical cyclones are further named (hurricane, typhoon) and can be classified by intensity.
Explain briefly: high sustained winds damage structures and uproot trees; torrential rain causes floods and landslides; storm surge inundates coastal areas; combined effects lead to large-scale destruction and loss of life.
Cyclones bring very strong winds, heavy rainfall, storm surges and flooding which destroy buildings, infrastructure, crops and cause casualties.
Explanation: clouds act like a blanket—during night they absorb and re-radiate terrestrial infrared radiation back to the surface, limiting heat loss. During the day clouds may reduce incoming solar radiation, but overall cloudy conditions, especially at night, result in warmer temperatures than cloudless conditions.
Clouds trap outgoing long-wave (infrared) radiation from Earth's surface, reducing nighttime cooling and keeping temperatures warmer than on clear nights.
Because fog limits the driver's sight distance, it makes speed judgment and reaction time difficult; it also affects pilots and ships, leading to traffic delays and accidents.
Fog greatly reduces visibility and can mask road hazards, increasing the risk of collisions and accidents.
During hot days the ground heats up, warm air rises, cools and condenses to form cumulonimbus clouds and heavy showers typically in the late afternoon—hence the informal name '4 o'clock rain'.
Convectional rainfall often occurs in the afternoon (around 4 p.m.) after daytime heating causes strong surface warming and convection, leading to showers and thunderstorms.
Explain: air over polar regions is extremely cold and stable; it descends and flows outward as easterlies. Cold air holds little moisture, so these winds are cold and dry.
Polar easterlies originate over cold polar high-pressure areas where air is cold and dry; the descending air and low evaporation keep humidity low.
Correct matches: 1 Meteorology → study of weather (5). 2 Climatology → study of climate (4). 3 Anemometer → measures wind speed (1). 4 Wind vane → shows direction of wind (2). 5 'Mare's tail' → a common name for cirrus clouds (3). 6 Leeward side → rain shadow region (7). 7 'Willy-willy' → term used in Australia for a dust devil/wind (6).
| # | Correct match |
|---|---|
| 1 | 5 |
| 2 | 4 |
| 3 | 1 |
| 4 | 2 |
| 5 | 3 |
| 6 | 7 |
| 7 | 6 |
Key differences: (1) Time scale — weather is short-term, climate is long-term average. (2) Variability — weather changes daily; climate describes typical patterns and extremes. (3) Use — weather used for forecasts; climate used for understanding regional conditions and planning.
Weather: Short-term atmospheric conditions (hours to days) at a place (temperature, humidity, precipitation). Climate: Average long-term patterns of weather (over 30+ years) for a region.
Differences: (1) Time — sea breeze during day, land breeze at night. (2) Direction — sea→land for sea breeze, land→sea for land breeze. (3) Cause — temperature contrast between land and sea producing pressure differences.
Sea breeze: daytime wind from sea to land caused by cooler sea air moving toward warmer land (onshore). Land breeze: nighttime wind from land to sea caused by cooler land air moving toward relatively warmer sea (offshore).
Key points: windward gets moist air uplift and heavy rainfall; leeward gets descending dry air and less precipitation (rain shadow).
Windward side: the side of a mountain or island facing the prevailing wind; receives more precipitation. Leeward side: the sheltered side away from prevailing wind; drier and often in the rain‑shadow.
Differences: origin (tropical oceans vs. mid-latitude fronts), energy source (latent heat of warm ocean vs. baroclinic instability), structure (eye and eyewall in tropical cyclones vs. frontal systems in temperate cyclones), and typical weather effects.
Tropical cyclone: forms over warm tropical oceans, has a warm core, organized circular storms with heavy rain and strong winds (called hurricanes/typhoons). Temperate (extratropical) cyclone: forms in middle latitudes along fronts between contrasting air masses, has cold/warm fronts and frontal precipitation patterns.
Include layer names, approximate heights, key features (weather in troposphere, ozone in stratosphere, meteors in mesosphere, ionisation and high temperatures in thermosphere) and note that composition changes (density decreases with height).
The atmosphere is layered: the troposphere (surface up to ~8–15 km) contains most of the air, weather and decreasing temperature with height; the stratosphere (to ~50 km) contains the ozone layer and temperature increases with height; the mesosphere (to ~85 km) where temperature falls again and meteors burn up; the thermosphere (to ~500–1000 km) with rising temperature due to solar radiation and ionisation; and the exosphere, the outermost sparse layer transitioning to space. Each layer has distinct temperature gradients and composition influencing weather, climate and radio communication.
Describe each: Trade Winds — reliable easterlies near equator used in sailing; Westerlies — dominant in mid-latitudes and influence temperate weather; Polar Easterlies — cold easterly winds at high latitudes. Mention cause: differential heating, pressure belts and Coriolis effect.
Permanent winds are global prevailing winds that blow consistently due to Earth’s rotation and pressure belts: the Trade Winds (NE in Northern Hemisphere and SE in Southern Hemisphere) blow from subtropical high belts toward the equatorial low; the Westerlies blow from the subtropical high toward higher mid-latitudes; and the Polar Easterlies blow from polar highs toward subpolar lows. These wind belts shape climate and ocean currents.
Explain briefly: High clouds are ice-crystal clouds above ~6 km; middle clouds are composed of water/ice at ~2–6 km; low clouds are below ~2 km and often bring drizzle or continuous rain; vertically developed clouds form from strong convection and can produce heavy rain and storms.
Clouds are classified by form and height: By form — Cirrus (thin, feathery), Cumulus (puffy, cotton-like), and Stratus (layered sheets). By height — High clouds (cirrus, cirrostratus, cirrocumulus), Middle clouds (altostratus, altocumulus), Low clouds (stratus, stratocumulus, nimbostratus) and Clouds with vertical development (cumulus, cumulonimbus). Each type has distinct appearance and weather associations (e.g., cumulonimbus → thunderstorms).
Give formation steps: low-pressure centre → convergence → ascent and condensation → latent heat release → rotation by Coriolis → mature cyclone. Then state classification: tropical vs. temperate, and mention intensity categories for tropical systems.
Formation: Cyclones form when a region of low pressure causes surrounding air to converge and rise; rising moist air cools and condenses releasing latent heat, strengthening the updrafts. The Coriolis force causes the system to rotate. Classification: Cyclones are mainly classified into tropical cyclones (forming over warm tropical oceans — hurricanes, typhoons, cyclones) and temperate (extratropical) cyclones (forming along mid-latitude fronts). Tropical storms are also categorized by intensity (tropical depression → tropical storm → cyclone/hurricane/typhoon).
Different Forms of Precipitation (concise definitions and formation):
1. Rain: Liquid water drops (diameter >0.5 mm) that fall from clouds when cloud droplets coalesce and become heavy enough to fall. Common in warm clouds and mid/low latitudes.
2. Drizzle: Very small, fine water drops (diameter <0.5 mm) that fall slowly from low stratus clouds; intensity is light.
3. Snow: Ice crystals or aggregates of ice crystals that form when atmospheric temperatures are at or below freezing in the cloud and below the freezing level to the ground. Snowflakes form by deposition of water vapour onto ice nuclei.
4. Sleet (ice pellets): Small translucent ice pellets formed when raindrops pass through a shallow layer of subfreezing air near the surface and refreeze before hitting the ground.
5. Hail: Hard, layered ice pellets formed inside strong cumulonimbus clouds with intense updrafts. Drops are carried upward, freeze in layers, and grow until heavy enough to fall.
6. Freezing rain: Rain that becomes supercooled and freezes on contact with surfaces at or below 0 °C, forming glaze ice.
7. Graupel: Soft, small snow pellets formed when snowflakes collect supercooled water droplets that freeze on contact; pellets are softer than hail.
Note: Whether precipitation reaches the ground as rain, snow, sleet or freezing rain depends on the vertical temperature profile between cloud base and surface.
Main forms: rain, drizzle, snow, sleet, hail (and graupel). Each forms under specific temperature and cloud conditions described briefly below.
Steps: 1) Draw four horizontal bands for high/middle/low/vertical. 2) Place cloud names in appropriate bands. 3) Add small sketches/photos and note appearance, typical weather (e.g., cumulonimbus → thunderstorms). 4) Label formation altitude ranges and common weather effects.
Create a chart listing cloud types by altitude: High (cirrus, cirrostratus, cirrocumulus), Middle (altostratus, altocumulus), Low (stratus, stratocumulus, nimbostratus), and Vertical development (cumulus, cumulonimbus). Include pictures and brief characteristics for each.
Activity suggestion: collect local and regional proverbs (including Tamil proverbs if available), note their meaning and any meteorological basis (e.g., red sky due to scattering indicates high pressure/weather patterns).
Examples of proverbs: "Red sky at night, shepherd's delight; red sky in morning, shepherd's warning." "When clouds are low, it will rain." "After rain comes fair weather."
Activity: Students may write short poems (2–8 lines) about clouds and rain, using imagery and simple rhyme; present in class or on a chart.
Short example poem:
"Clouds gather soft and gray,
Whispers in the wind, then rain."
Sample Week‑long Cloud Observation Report (concise):
Day 1 (Mon): Morning – Cirrus (thin, wispy, white) → indicates fair weather. Afternoon – Cumulus (puffy, white with flat base) → fair with some vertical growth.
Day 2 (Tue): Cumulus congestus (taller, white tops, darker bases) → developing instability; short showers possible.
Day 3 (Wed): Stratus (low, uniform grey layer) → overcast; light drizzle in evening.
Day 4 (Thu): Altocumulus (patchy, white/grey, rounded masses) → mid‑level clouds; cooler morning.
Day 5 (Fri): Cumulonimbus (towering, anvil top, dark base) → thunderstorms in late afternoon with heavy rain and lightning.
Day 6 (Sat): Scattered cumulus (small, white) → clearing, pleasant.
Day 7 (Sun): High cirrostratus (thin veil, pale halo around sun) → approaching frontal system.
Colour notes: Most clouds appeared white when sunlit and grey to dark grey at base when thicker or water‑laden. Red/orange hues were observed during sunrise/sunset when sunlight passed through more atmosphere.
Conclusion: During the week cloud types varied from high thin cirrus to low thick cumulonimbus. Darker bases and thicker clouds correlated with precipitation events.
(Students should record actual daily observations with time, cloud type, colour, and any weather changes.)
Sample 1‑week cloud observation report summarising cloud types, shapes and colours with brief interpretation.
How to collect the data:
- Use a reliable source such as the India Meteorological Department (IMD) website, local meteorological station, or reputable weather services (e.g., IMD.gov.in, weather.gov, or national/local weather apps). Note the date and time (UTC or IST) when values are reported.
- Record maximum and minimum or observed temperature and rainfall (in mm) for the specified 24‑hour period.
Sample data (EXAMPLE only — obtain actual values for your date):
Temperatures (°C) for the day (sample):
- Kanniyakumari: 28.0 °C
- New Delhi: 35.0 °C
- Allahabad: 34.0 °C
- Itanagar: 26.0 °C
Rainfall (mm) for the day (sample):
- Jaisalmer (Rajasthan): 0.0 mm
- Mawsynram (Meghalaya): 180.0 mm
- Nagapattinam: 12.0 mm
- Coimbatore: 1.5 mm
How to present: Create a table with columns: Location | Date | Observation time (IST) | Temperature (°C) or Rainfall (mm) | Source (URL or station name).
Remark: The sample numbers are illustrative. For assessment, attach a screenshot or citation of the source showing the actual reported values for the chosen day.
Instructions to collect the requested data and an example (sample) data table. Students must collect current actual data from a reliable source (IMD, local station, weather websites).
Template for weekly local weather record (fields to fill each day):
- Date | Time | Maximum temp (°C) | Minimum temp (°C) | Sky (sunny/cloudy/overcast) | Precipitation (mm) | Wind speed & direction | Humidity (%) | Pressure (hPa) | Remarks
Concise example (sample values for 7 days):
Day 1: 2026-06-01 | 09:00 IST | Max 34 | Min 26 | Partly cloudy | 0.0 mm | 10 km/h E | 60% | 1008 hPa | Warm afternoon
Day 2: 2026-06-02 | 09:00 IST | Max 33 | Min 25 | Overcast | 2.0 mm | 12 km/h SE | 72% | 1006 hPa | Light shower in evening
Day 3: 2026-06-03 | 09:00 IST | Max 30 | Min 24 | Cloudy | 5.0 mm | 15 km/h S | 78% | 1004 hPa | Moderate rain
Day 4: 2026-06-04 | 09:00 IST | Max 31 | Min 24 | Cloudy | 0.0 mm | 8 km/h SW | 70% | 1007 hPa | Humid
Day 5: 2026-06-05 | 09:00 IST | Max 35 | Min 26 | Sunny | 0.0 mm | 10 km/h W | 55% | 1009 hPa | Hot and dry
Day 6: 2026-06-06 | 09:00 IST | Max 32 | Min 25 | Scattered clouds | 0.5 mm | 14 km/h NW | 65% | 1006 hPa | Brief drizzle
Day 7: 2026-06-07 | 09:00 IST | Max 31 | Min 24 | Partly cloudy | 0.0 mm | 9 km/h N | 63% | 1008 hPa | Comfortable
Note: The example values are illustrative. For school work, students should record their own measurements/observations each day and may use household thermometers, rain gauge, anemometer (if available), and local weather station reports for verification.
Provide a 7‑day weather record template and a short filled example. Students must record actual observations daily.
a) Simple Rain Gauge (materials & procedure):
Materials: a clean, straight‑sided plastic bottle (1–2 L), ruler, marker, scissors, stones/sand (for weighting), funnel (optional).
Procedure: Cut the top off the bottle about one third from the top. Invert the top part as a funnel and fit into the base or use the open bottle mouth as the collector. Place a ruler along the inside of the bottle and mark millimetre/centimetre graduations from the base upward. Fix the bottle upright on a flat, open surface away from roofs or trees. After rain, read the water level against the ruler to record rainfall in mm. Empty and reset after each reading.
Usage notes: Place the gauge in an open area, level it, and record readings at consistent times (e.g., 09:00 IST daily). For accuracy use a wider‑mouth container and ensure the collector rim is 30 cm above ground.
b) Simple Wind Vane (materials & procedure):
Materials: a stiff cardboard or thin plywood, a drinking straw, a straight pin or nail, a wooden dowel or pencil, a small weight (clay), compass for orientation.
Procedure: Cut an arrow shape from cardboard (larger tail to catch wind). Push the straight pin through the middle of the straw and fix the pin vertically onto the top of the dowel so the straw can rotate freely. Attach the arrow to the straw so it balances and rotates easily. Place the vane on a mounting post at least 1–2 m above ground in an open area.
Usage notes: Use a compass to mark North. When the vane settles, the arrow points into the wind (pointing from where the wind comes). Record wind direction at regular intervals.
Safety and accuracy tips: Ensure the wind vane rotates freely; avoid nearby obstructions that create local turbulence. Calibrate and check models against a known instrument if available.
Short instructions to build simple models and how to use them to measure rainfall and wind direction.