Sunlight is solar radiation visible on the Earth’s surface. Britannica reports that it is divided into three categories: visible light, ultraviolet (UV) light and infrared radiation. It has at least two effects on the human brain. One has to do with vitamin D, which helps with bone health. The other is the prevention of depression in some people. All in all, in the broadest sense, humans cannot live without it.
The sun burns at a temperature of about 10,000 degrees Fahrenheit. Not all that heat reaches the earth’s surface because it is absorbed by the ozone layer. So that is all type C UV radiation and most of type B. It is type A that reaches us at full strength.
When the sun directly hits the top of the atmosphere, the average intensity of solar energy is 1,360 watts per square meter. By way of comparison, a microwave uses 1,000 watts, and an incandescent light bulb 40 to 100 watts. Solar energy is also measured in joules. One joule equals one watt of power radiated or dissipated for one second over the earth’s surface.
The spherical shape of the earth means sunlight disperses unevenly across the globe, and of course across America. Using data from the Centers for Disease Control and Prevention (CDC) for 2015, the latest year for which information is available, 24/7 Wall St. chose the state with the most sunlight based on the annual average daily dose of UV irradiance, or the output of light energy from the sun, as measured on earth. (Data was not available for Alaska and Hawaii.) All measurements are in joules per square meter.
For sun worshippers, the place to be is probably what you’d expect: Arizona. Its Sunbelt neighbor, New Mexico, follows, and then the Sunshine State itself, Florida. Of the top 10 states for sunlight, all except Colorado are either Sunbelt or Southern states. Prefer a cooler, less sunny climate? Go north to Maine or North Dakota. The 10 states with the least amount of sunlight can be found in New England or the Upper Midwest.
As mentioned, the state with the strongest sunlight is Arizona. Here are the details:
- Annual average daily sunlight: 3,728 J/m2
- 10-year change in average daily sunlight: +4% (19th smallest)