Sunshine through a dusty window

Описание: Sunlight:
Sunlight is a portion of the electromagnetic radiation given off by the Sun, in particular infrared, visible, and ultraviolet light. On Earth, sunlight is filtered through Earth's atmosphere, and is obvious as daylight when the Sun is above the horizon. When the direct solar radiation is not blocked by clouds, it is experienced as sunshine, a combination of bright light and radiant heat. When it is blocked by clouds or reflects off other objects, it is experienced as diffused light. The World Meteorological Organization uses the term "sunshine duration" to mean the cumulative time during which an area receives direct irradiance from the Sun of at least 120 watts per square meter.[1] Other sources indicate an "Average over the entire earth" of "164 Watts per square meter over a 24 hour day".[2]

The ultraviolet radiation in sunlight has both positive and negative health effects, as it is both a principal source of vitamin D3 and a mutagen.

Sunlight takes about 8.3 minutes to reach Earth from the surface of the Sun. A photon starting at the center of the Sun and changing direction every time it encounters a charged particle would take between 10,000 and 170,000 years to get to the surface.[3]

Sunlight is a key factor in photosynthesis, the process used by plants and other autotrophic organisms to convert light energy, normally from the Sun, into chemical energy that can be used to fuel the organisms' activities.
https://en.wikipedia.org/wiki/Sunlight

United States:
The United States of America (USA), commonly known as the United States (U.S.) or America (/əˈmɛrɪkə/), is a federal republic[16][17] composed of 50 states, a federal district, five major self-governing territories, and various possessions.[fn 6] Forty-eight states and the federal district are contiguous and located in North America between Canada and Mexico. The state of Alaska is in the northwest corner of North America, bordered by Canada to the east and across the Bering Strait from Russia to the west. The state of Hawaii is an archipelago in the mid-Pacific Ocean. The U.S. territories are scattered about the Pacific Ocean and the Caribbean Sea, stretching across nine official time zones. The extremely diverse geography, climate and wildlife of the United States make it one of the world's 17 megadiverse countries.[19]
At 3.8 million square miles (9.8 million km2)[20] and with over 324 million people, the United States is the world's third- or fourth-largest country by total area,[fn 7] and the third-most populous. The capital is Washington, D.C., and the largest city is New York City; twelve other major metropolitan areas—each with at least 4.5 million inhabitants—are Los Angeles, Chicago, Dallas, Houston, Washington, D.C., Philadelphia, Miami, Atlanta, Boston, San Francisco, Phoenix, and Riverside.
https://en.wikipedia.org/wiki/United_...