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KS3 · 15 minutes · no login
Cyclone and anticyclone
All teacher notes · Open the lab · 2026 words · ·
Why this lesson, and why the 3D
Cyclone and anticyclone is a fifteen-minute projector lesson, not a homework packet and not a film with a quiz bolted on. Put this hook on the board before you dim the lights: A midlatitude cyclone is a spinning comma of fronts, not a hurricane. By the end of the slot a pupil should be able to contrast a NH cyclone (anticlockwise, low) with an anticyclone (clockwise, high), and attach fronts to the low. Curriculum tags in the header (KS3; GCSE weather; NGSS MS-ESS2-5) are filters, not a flag. The room is worldwide; SI first; International English. Ages on the card (KS3, GCSE, NGSS MS) are a suggested band, not a gate.
Do not call a UK windy day a hurricane unless the Met Office does. A winter depression approaching London is a midlatitude cyclone: a low, a comma of fronts, anticlockwise in the northern hemisphere. An anticyclone is the other machine: high, clockwise, sinking, often clearer, and still able to sit a freezing fog over a British morning. Sandy is a hybrid caution, not a licence to mix the words. GCSE wants depression versus anticyclone and the spin. NGSS wants low versus high and why one rains. Phoenix heat is not this lab; Florida’s hurricane is a later engine. If pupils hear cyclone and see an eyewall, they will misread every Met Office chart. Name the family. Then name the member.
The 3D is a named, inspectable object. Click the part, not a caption. If the model will not spin, the Why panel still carries the mechanism, the two photographs, and the film. Do not apologise for the model. Drive it. A silent spin teaches a screensaver. A named mesh that changes under a slider teaches the process.
Fifteen minutes on the projector
Leave Anticyclone off. Low in the middle, isobars, anticlockwise in the northern hemisphere. Attach the fronts on the comma. This is a midlatitude cyclone, a depression. Cyclone does not mean hurricane. That is the misconception. Cyclone is the family. Tropical cyclone is one member. Midlatitude depressions are another. Toggle Anticyclone on. High, clockwise in the northern hemisphere, sinking, often clearer. Sink, compress, warm, dry. Not a guarantee of sunshine in a British winter fog. Ask which one rains. The low, usually, if the fronts are working. A UK winter depression is this machine, not an eyewall. Do not mix northern- and southern-hemisphere spin. Names matter more than the word cyclone alone. Finish in Check.
Open the lab full screen (F). Labels on (L). Speak the first step before you touch a slider: Low in the middle, isobars, anticlockwise in NH. Fronts on the comma. Then the second: Toggle anticyclone: high, clockwise, sinking, often clearer. Then the third: Names: depression / cyclone vs anticyclone. Tropical cyclones are a later lab.
The sliders that earn their keep are Anticyclone. Space plays; arrows nudge time; R resets. Parameters the URL can remember: anti. If you only have eight minutes, skip the last step and finish in Check. Projector layout (P) is for the back row: one idea, large type, the model still live.
Leave Anticyclone off to start. Space plays the comma so the fronts rotate with the low. Arrow keys freeze a spoke for the board. L hides labels; ask for spin before you reveal. R resets the toggle. P is projector. Toggle Anticyclone on for the high, clockwise, sinking story, then off again so the depression is the default. Time is a process clock, not a year. Share the URL on the low, then on the high, and do not leave both stories unnamed when the class walks out.
The in-site film is “Natural Hazards: Crash Course Geography #24” (Crash Course Geography, about 11 min, Crash Course / Complexly on YouTube. Standard YouTube licence. Educational embed, autoplay off.). Autoplay is off. Play one minute if you need a second voice; do not let the film eat the slot. The 3D still has to move under your hand.
What the third row will get wrong
You will hear the misconception before you have finished the first sentence. Write the false claim on the board and leave it there until the model has contradicted it. Do not skip this. A fluent pupil can recite the hook and still believe the false sentence.
“Cyclone means hurricane.” — no. Cyclone is the family. Tropical cyclone is one member. Midlatitude depressions are another.
“High pressure always means sunshine.” — no. Sink, compress, warm, dry: often clearer. A British winter anticyclone can still sit fog and stratus under the lid.
“Northern- and southern-hemisphere cyclones spin the same way.” — no. NH cyclone anticlockwise, SH cyclone clockwise. Flip the hemisphere and the diagram must flip.
Pitfalls to keep in your pocket: NH/SH spin mix-up. One word ‘cyclone’ for two machines. Promising sunshine under every anticyclone. Calling a UK gale a hurricane without the Met Office. Do not let a pupil leave thinking the 3D is a photograph. It is a teaching model. Where vertical exaggeration exists, T collapses it and the caption says so. A labelled lie of scale is honest. An unlabelled one is a cartoon.
Two places, not a slogan
In the northern hemisphere, air flows in toward a surface low and Coriolis deflects it right, so the cyclone spins anticlockwise. Fronts attach to that low as a comma: warm front, cold front, then occlusion as the system matures. That is a midlatitude cyclone, a depression in UK exam language, extra-tropical in adult charts. It is not a tropical cyclone. Tropical cyclones have an eye and an eyewall and live on warm ocean; they are a later lab. Toggle anticyclone and the centre is a high: air sinks, compresses, warms, and dries, so skies are often clearer, and the NH spin is clockwise. Sinking is not a guarantee of sunshine in a British winter anticyclone; fog and stratus can sit under the lid. Southern-hemisphere spin flips; do not mix the diagrams. Ask which one rains. The low, usually, if the fronts are working. A UK sea breeze is a local thermal loop, not a cyclone. Phoenix heat is a budget story, not a spinning comma. Keep the word cyclone as the family, then attach midlatitude or tropical so the third row cannot swap the machines.
The first place to land is UK depression. The second is Sandy as a hybrid caution. Same process, different rock or climate. If a pupil can only name one place, they have a postcard, not a mechanism. Atlas entries for those names are a click from the case list; send them back to the lab with one sentence they can say in Check.
Do not flatten the comparison into “this country versus that country.” Name the landform. Holderness is till, not chalk. Hawaii is a hotspot, not an island arc. Yosemite is a glacial trough, not a river canyon. The 3D is allowed to be schematic; the place names are not allowed to be sloppy.
Figures and the film
Field photograph: An extratropical cyclone as a comma cloud. An extratropical cyclone as a comma cloud. This is the classroom sense of cyclone-anticyclone: a named landform, process, or object. Source: Wikimedia Commons / NASA / USGS / NOAA, public domain or CC. Credit: Wikimedia Commons / NASA / USGS / NOAA, public domain or CC.
Mechanism photograph: Field photograph or official scientific figure for teaching cyclone anticyclone. Field photograph or official scientific figure for teaching cyclone anticyclone. A second photograph for the projector script — not the lab cover. Source: Wikimedia Commons / NASA / USGS / NOAA, public domain or CC. Credit: Wikimedia Commons / NASA / USGS / NOAA, public domain or CC.
Two photographs, two jobs. The field picture is the place. The mechanism picture is the process. Do not run the lesson on a single Apollo Earth disc. A carbon-cycle class is a forest and a seam, not a blue marble. An ENSO class is a Pacific temperature map, not Africa from Apollo 17.
Words they must be able to say
Say these out loud once while you click the matching mesh. If a word has no mesh, it still has a photograph in Terms.
Cyclone: Low-pressure system. Midlatitude: fronts. Tropical: eye and eyewall, a later lab. Anticyclone: High-pressure system. Sinking air, often clearer, not a sunshine guarantee in winter fog. Depression: UK exam name for a midlatitude cyclone. Convergence: Air flowing together. At a surface low it feeds rise. Divergence: Air spreading apart. Aloft over a low, or at the surface of a high. Comma cloud: The satellite signature of a mature midlatitude cyclone, fronts on the tail. Extra-tropical: Outside the tropics. A midlatitude depression is extra-tropical; a hurricane is not.
Exam-language toggle (the Teacher tab) swaps UK/US pairs where they exist — levée/levee, arête/arete — so a mixed room is not punished for spelling.
Close the slot
If JavaScript or WebGL dies, the 2D fallback still shows a low and a high. Teach from the steps: anticlockwise comma with fronts, then the anticyclone. Check still names northern-hemisphere spin, sinking under a high, and why a UK depression is not a hurricane. Print the teacher script. The glossary still carries depression, comma cloud, and extra-tropical. You lose the rotating comma, not the vocabulary. A Met Office chart can stand in for the canvas; point at the low, then at the high, and refuse the word hurricane unless it is earned.
Finish in Check — ten questions, not a mood. The bank mixes definition, process, the misconception you just killed, a named place, and a read-the-model item (click the part; T). If a pupil can only recite the hook, they have not used the geometry. Wrong answers still show the one-line explain. Do not skip the explain.
Sources on the Teacher tab are the trail, not a bibliography to copy. Met Office depressions; NOAA extra-tropical.
Link back to the live lab and keep the same slug. Do not invent a parallel worksheet that contradicts T, SI, or the named parts.
This note is worldwide. Curriculum tags (KS3; GCSE weather; NGSS MS-ESS2-5) are filters, not a flag. A class in Nairobi, London, or Shanghai can use the same 3D. Ages (KS3, GCSE, NGSS MS) are a suggested band. If a sentence only works in one exam board, rewrite it before you project it.
Write these three lines on the board before you dim the lights. One: A midlatitude cyclone is a spinning comma of fronts, not a hurricane. Two: the misconception “Cyclone means hurricane.”. Three: the named parts they must click. Then drive the model. Check is ten questions covering definition, process, the misconception, a place, and a read-the-model item. Do not skip the explain on a wrong answer.
Board, units, and what not to say
SI first. Metres, kilometres, degrees Celsius, metres per second. A conversion in brackets is courtesy, not a second system. Do not let a pupil leave thinking the 3D is a photograph. It is a teaching model. Where vertical exaggeration exists, T collapses it and the caption says so.
Do not say “teaching mesh”, “sprinkle”, or “thin free surface not a fat pipe” out loud. Say the landform. Seasons are ~23.44° of axial tilt, not Earth–Sun distance. The outer core is liquid; S-waves do not pass. Yosemite is a glacial U-trough. San Andreas is a transform. Hawaiʻi and Yellowstone are hotspots. Florida is not a glacial trough.
If the room is noisy, projector layout (P) is the back-row setting: one idea, large type, the model still live. Full screen (F). Labels (L). Space plays. Arrows nudge time. R resets. The URL can remember anti. Send them home with the same link; there is no login.
Do not call a UK windy day a hurricane unless the Met Office does. A winter depression approaching London is a midlatitude cyclone: a low, a comma of fronts, anticlockwise in the northern hemisphere. An anticyclone is the other machine: high, clockwise, sinking, often clearer, and still able to sit a freezing fog over a British morning. Sandy is a hybrid caution, not a licence to mix the words. GCSE wants depression versus anticyclone and the spin. NGSS wants low versus high and why one rains. Phoenix heat is not this lab; Florida’s hurricane is a later engine. If pupils hear cyclone and see an eyewall, they will misread every Met Office chart. Name the family. Then name the member.
In-site film
Natural Hazards: Crash Course Geography #24. Crash Course Geography. Crash Course / Complexly on YouTube. Standard YouTube licence. Educational embed, autoplay off. Autoplay off.