UV Tracker & Vitamin D: RayDay
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RayDay is the ultimate sun seeker's companion — a vitamin D and UV tracker that tells you exactly when the sun is high enough each day for your body to produce vitamin D naturally. Using NOAA solar position algorithms and real-time atmospheric data, RayDay calculates your personal "D-Window" — the precise time between sunrise and sunset when UVB rays can penetrate the atmosphere (sun altitude above 35°). No guessing, no generic advice — just science-based timing personalized to your location and skin type. FIND YOUR D-WINDOW Know exactly when vitamin D production is possible. RayDay shows today's and tomorrow's D-Window with a beautiful animated solar path arc. Watch the sun beam across the sky from morning daylight through golden hour to sunset. TRACK VITAMIN D LIVE Start a sun session timer and track your vitamin D production in real-time. See your IU accumulate with a stunning progress ring, monitor your UV index exposure, and know exactly when you've reached your daily goal. PROTECT YOUR SKIN Stay safe in the sunshine with a built-in burn countdown timer. RayDay personalizes everything to your Fitzpatrick skin type (I–VI), clothing level, and SPF sunscreen — so you get the glow without the burn. Safe tanning starts with knowing your limits. PLAN YOUR WEEK Check the 7-day forecast to see your D-Window for the coming week. Each day shows the start time, duration, and peak sun angle so you can plan outdoor sessions when rays are strongest. EARN SUN BADGES Stay motivated with 20 collectible badges. Earn streaks, session milestones, IU achievements, and special badges like Globe Trotter and Golden Hour. Your sunshine journey, gamified. MORE FEATURES • Live Solar Path — Animated arc showing sun position from sunrise through sunset • Atmospheric Dashboard — Real-time UV index, cloud cover, altitude, and humidity • Smart Notifications — Get a notify alert 15 minutes before your D-Window opens • Home Screen Widget — Quick glance at your D-Window and sun status • SPF & Sunscreen Support — Factor in your sunscreen protection level • Snow & Sand Albedo — Automatic UV reflection adjustments for snow, sand, and water • 30 Languages — Fully localized for worldwide use • Phase-Aware Design — App colors shift with daylight: dawn sunglow, morning beam, sunset glow • Works Everywhere — Accurate for any latitude, including polar regions HOW IT WORKS RayDay uses NOAA solar position algorithms to calculate the sun's altitude throughout the day. When the sun crosses 35° above the horizon, UVB rays penetrate the atmosphere — that's your D-Window for vitamin D synthesis. The app factors in your skin type, clothing, and SPF to recommend safe exposure durations using Holick's Rule for vitamin D production. DISCLAIMER: RayDay is for educational and informational purposes only. It is not a medical device. Consult a healthcare professional for advice about vitamin D supplementation and sun exposure. Studies referenced: Holick MF (2007, PMID: 17634462), Webb AR (2006, PMID: 16529140). --- LEGAL: Privacy Policy: http://www.jakubl.com/privacy.html Terms of Use (EULA): http://www.jakubl.com/terms.html SUPPORT: support@jakubl.com X: @jakublaszczyk
