This map marries together the sun and UV lines of latitude with the Earth's magnetic lines.
Check the available to interact with it.
About this map
This map follows the ideas of Dr. Jack Kruse, a retired neurosurgeon, author, and founder of the Kruse Longevity Center. His work explores his theories about light, water, magnetism, and mitochondrial function. He argues that where you live matters more for health than what you eat. He stresses two things about a place: strong sunlight, which favours low latitudes, and a strong, stable magnetic field, which favours low declination and steers away from weak-field regions.
The lines come from physics. The sun lines are geometry. The magnetic lines come from the IGRF-14 field model, which covers 2020 to 2030. Later years extend the 2025 to 2030 trend. Tested against past data, a 15-year projection like this was typically off by about 0.3° and at worst about 1°.
The 45° sun rule for vitamin D is a rough guide, and real UVB also depends on altitude, ozone and cloud.