KIRAKU is an interactive app for learning how the sky and weather work, with animated visuals and simple controls. Why do clouds form where they do? How do raindrops grow? Why do typhoons love warm seas? Change the conditions yourself and see.
Developer: Fuji Bit Inc.
The meteorology edition of the RAKU science series, from school earth science to introductory meteorology, with real numbers and examples.
11 simulations in 3 categories:
How the atmosphere works:
- Vertical structure: temperature and pressure from the ground up to 120 km (standard atmosphere): the four layers, the ozone layer, and conditions at Mount Fuji, Everest and airliner altitude.
- How clouds form: change the surface temperature, humidity and stability, and see where the cloud base and top form and why you get cumulus or a towering cumulonimbus.
- How rain forms: compare warm rain (droplets merging) with cold rain (ice crystals growing). The updraft sets drop size and fall speed; the surface temperature decides rain, sleet or snow, and strong updrafts make hail.
- Foehn wind (new): moist wind rains out on the windward side and comes down the lee side hot and dry. Change the temperature, humidity and mountain height.
Changing weather:
- Fronts and lows: follow a low from birth to occlusion on a weather map and in cross-section, and watch the temperature and wind change as each front passes.
- Typhoons: warm or cool the sea and watch the peak wind, central pressure and intensity class change, with the eye, eyewall and spiral rainbands.
- Radar and satellite: switch between radar (dBZ) and infrared and visible satellite images to read rain, cloud height and thickness.
- Sea and land breezes (new): land and sea warm differently, so the wind turns around between day and night, with calm in the morning and evening.
Earth's climate:
- Global circulation: the Hadley, Ferrel and polar cells and the trade winds, westerlies and polar easterlies, through the seasons and on a non-rotating Earth.
- Jet stream: meandering westerlies (Rossby waves) seen from above the North Pole. Wind speed and wave number decide whether waves move or stall into a block.
- El Niño and La Niña: change the trade winds and watch the Pacific's warm water and rain shift east or west.
Features:
- Clean, modern design (switch between dark and light themes)
- Home screen organized by category, plus an "All modes" list
- Tips and a play button in the control panel
- Results change in real time as you move sliders and choices
- An explanation sheet with formulas, terms and real examples for every simulation
- Canvas and controls side by side in landscape and on large screens
- Supports larger text sizes
- 73 languages including English and Japanese (follows your device language)
- No sign-in; start exploring right away
- An educational simulator: it does not show real forecasts or warnings
Price and purchases:
- Price: Free
- In-app purchases: none
- Subscriptions: none
- Ads: a Pangle banner ad at the bottom of the screen
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