Make a tornado appear indoors!

1) Overview

You’ll create a visually convincing, controllable indoor “tornado”—a vertical air vortex made visible with safe fog or mist—inside a clear enclosure (desktop-size) or a small walk-in booth (room-size). We deliberately avoid dangerous wind speeds, flammable smoke, and open water hazards. The plan blends known “vortex chamber” designs (counter-rotating inflow + upward draft) with venue-friendly safety (acrylic walls, filtered fog, HEPA extraction, and HVAC isolation). I arrived at this by weighing three constraints: (1) realism on camera, (2) repeatable control, (3) safety/compliance indoors.

2) Rationale for Success

• Physics-backed: A visible vortex requires three ingredients—spin (tangential inflow), lift (updraft), and tracer (fog/mist). We engineer each input with fans and a fog source in a shaped enclosure so the vortex forms where we want, when we want.

• Visibility > violence: Camera “wow” comes from coherent structure + lighting, not dangerous wind. A laminar, gently rotating core looks more “tornado-like” than a chaotic blast.

• Venue-safe stack: Sealed or semi-sealed acrylic keeps fog contained; top extraction prevents stray haze from triggering smoke detectors; GFCI and low-voltage gear keep electrical risk low.

3) Task List (3 levels deep)

Phase 0 — Define the win (30 min)

1. Success criteria

   • a) Vortex height ≥ 60% of enclosure height.

   • b) Core visibly continuous for ≥ 15 seconds on command.

   • c) No HVAC/smoke-alarm triggers, no water on floor.

2. Constraints

   • a) Indoor only; shared HVAC requires isolation plan.

   • b) Max sound level (e.g., <60 dBA at 1 m) for filming.

   • c) Fog allowed only if detectors isolated/covered by facility per policy.

Phase 1 — Pick your scale (choose one)

1. Desktop Tornado Tube (safest, fastest)

   • a) Enclosure: clear acrylic cylinder (Ø 25–30 cm, height 60–90 cm) or hexagonal tube.

   • b) Updraft: 1× quiet inline duct fan at lid (100–150 CFM).

   • c) Spin: 6–8 angled side inlets near base (30–45°) driven by small PWM-controlled fans or passive vents.

2. Mini Booth (walk-in, still safe)

   • a) Enclosure: 1 m × 1 m footprint, height 2 m, acrylic + aluminum T-slot frame.

   • b) Updraft: 1–2 inline fans (200–400 CFM total) plus HEPA filter on exhaust.

   • c) Spin: ring of 8–12 low-noise fans at ~30 cm height, skewed 30–45° to induce rotation.

Phase 2 — Bill of Materials (indicative)

1. Structure

   • a) Acrylic sheets/tube (4–6 mm), T-slot extrusions, corner brackets.

   • b) Neoprene gaskets, silicone sealant, latchable service panel.

2. Air system

   • a) Inline duct fan(s) with PWM or triac controller; flexible duct to top exhaust.

   • b) 40–80 mm side fans (quantity per scale); fan grills, finger guards.

3. Fog/Tracer

   • a) Water-based fog machine (theatrical, non-oil) or 1–2 ultrasonic humidifiers.

   • b) Fog fluid (water/glycol mix) or distilled water for ultrasonic units.

4. Control & Power

   • a) PWM fan controller(s); smart plug for fog; GFCI power strip; cable management.

   • b) Handheld anemometer, IR thermometer (optional, for tuning).

5. Safety & Cleanliness

   • a) HEPA filter on exhaust path; absorbent mat at base; nitrile gloves; eye protection.

   • b) Detector covers only if permitted and with fire-safety approval.

Phase 3 — Build (half-day desktop; 1–2 days booth)

1. Enclosure

   • a) Cut/assemble acrylic; seal seams; install top plate with fan cutout.

   • b) Add side fan mounts (drill at 30–45° tangential angle); add lower intake plenum if using passive vents.

   • c) Install service door/panel with gaskets.

2. Air path & extraction

   • a) Mount top inline fan drawing upwards; route duct to a window or HEPA box.

   • b) Verify one-way flow: smoke pen test—air should enter low, exit high.

3. Electrical

   • a) Route cables externally; label circuits; test GFCI; strain relief on all leads.

   • b) Set PWM controllers to mid-range to start.

Phase 4 — Commissioning & Tuning (2–3 hours)

1. Dry run (no fog)

   • a) Updraft only: confirm steady upward flow; note airflow at base with tissue test.

   • b) Add spin: energize side fans; verify gentle swirl without recirculation.

   • c) Use anemometer: target ~0.5–1.5 m/s centerline updraft (desktop), 1–2 m/s (booth).

2. Fog integration

   • a) Introduce fog at base (upstream of swirl) slowly; avoid flooding.

   • b) Adjust: increase spin until a coherent column forms; then trim updraft to stretch it.

   • c) If column breaks: reduce updraft or lower fog density; check for cross-breezes.

3. Lighting & camera

   • a) Side-light at ~45° with softboxes; backlight rim for contrast.

   • b) Use darker backdrop; shoot at 1/120–1/240 shutter to crisp the structure.

   • c) White balance on acrylic, not fog.

Phase 5 — Operations & Reset (30–60 min)

1. Run procedure

   • a) Start extraction → start updraft → start side fans → introduce fog (slow ramp).

   • b) Hold shot; pulse fog to maintain semi-transparent core.

   • c) Stop fog → run fans 2–3 minutes to clear.

2. Cleanup

   • a) Wipe interior condensate; check for slipping hazards.

   • b) Replace HEPA if visible loading; coil cables; log run settings.

4) Obstacles & Countermeasures (with reasons)

• Obstacle: Building HVAC drafts collapse the vortex.
  Countermeasure: Use an enclosure (acrylic walls) and top-only exhaust so room flows don’t shear the column; schedule runs when HVAC is idle. Reason: Shear destroys laminar core.

• Obstacle: Smoke detectors / venue policy.
  Countermeasure: Prefer ultrasonic humidifiers (visible “steam-like” mist). If fogger: use water-based fluid, minimal density, and exhaust through HEPA; coordinate with facility management before covering or isolating detectors. Reason: prevent false alarms and stay compliant.

• Obstacle: Fog over-saturates, obscuring the core.
  Countermeasure: Pulse fog; increase updraft a notch; add mesh flow straighteners above inlets. Reason: less tracer = more coherent, camera-friendly structure.

• Obstacle: Loud fan noise on mic.
  Countermeasure: Use quiet inline fans, rubber isolators, and record MOS (no sync sound) with separate VO. Reason: sound quality without compromising airflow.

• Obstacle: Condensation slicks on floor.
  Countermeasure: Raised lip at base, absorbent mat, short runtime; wipe-down between takes. Reason: slip prevention.

5) Safety & Compliance

• Electrical: All devices on GFCI; no liquids above outlets; drip loops on cables.

• Respiratory: Water-based fog or humidifier mist; avoid oil-based haze; ventilate; limit exposure time.

• Fire/Life Safety: Never disable detectors without written approval; keep class ABC extinguisher on site; keep exits clear.

• Mechanical: Finger guards on all fans; no loose clothing near inlets.

6) Configuration Presets (quick start)

• Desktop: Top fan ~60% PWM; side fans ~40%; fog 2-3 sec pulses every 10–15 sec.

• Booth: Top fans ~50–70%; ring fans ~50%; fog low & continuous until column forms, then pulse.

7) Acceptance Test

1. From cold start to stable column in ≤ 60 seconds.

2. Maintain a continuous column ≥ 15 seconds three times in a row.

3. No fog leakage observed at 1 m from enclosure; no alarm events; surfaces dry within 5 minutes after shutdown.

8) What’s Not Possible / Limits (clear, honest)

• No real destructive tornado: Indoor-safe vortices won’t topple furniture or fling objects; wind speeds remain modest.

• Open-room “free” tornado is unstable—you’ll get wisps that break up. Use an enclosure for reliability.

• Certain venues (hospitals, high-sensitivity detectors) may prohibit any fog/mist; use CGI or AR overlays in those cases.

• Perfect vertical “needle” every time is unrealistic; expect minor wobble and 1–3 tuning attempts per take.

9) Optional Upgrades (nice to have)

• Flow straightener (honeycomb) above lower plenum for cleaner core.

• DMX or microcontroller to sync fog pulses and fan PWM for “on-cue” formation.

• LED backlight (cool white) with barn doors for dramatic edges; polarized filter on lens to manage acrylic glare.

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One Last Thing

If anyone asks how you made a tornado indoors, tell them you house-trained the weather—it only spins when you say “roll.” 🌪️🐶