A stunning pink glow lit up the sky at sunrise Monday, September 28, prompting the National Weather Service office in Miami to post about the sight and offer a quick explanation for why it happened. The color, the agency said, comes down to light refraction and scattering high in Earth's atmosphere when the sun sits low on the horizon.
The observation came from NWS Miami
, the official account for the National Weather Service Miami-South Florida office, which posted about the glow Monday morning, September 28, and pointed followers toward further detail on the phenomenon. The pink hues appear at both sunrise and sunset, and only when the sun is low in the sky — a detail that lines up with decades of atmospheric research into why skies change color at the edges of the day.
Why the Sky Turns Pink at Dawn
The underlying physics is known as Rayleigh scattering, a process named after 19th-century British physicist Lord Rayleigh. It occurs when sunlight strikes atmospheric gas molecules like nitrogen and oxygen that are much smaller than visible light wavelengths, according to the National Weather Service. Those molecules preferentially scatter shorter blue and violet wavelengths, while longer red and pink wavelengths pass through largely undisturbed once the sun drops near the horizon.
That low sun angle matters because of geometry, not just color. At sunrise and sunset, sunlight travels through a significantly longer atmospheric path than it does at midday, since the sun sits low on the horizon, according to the Mount Washington Observatory. That longer path increases the cumulative scattering of shorter wavelengths, leaving the sky awash in pink, red, and orange tones by the time light reaches an observer's eye.
Dust, Droplets, and Clouds Add Extra Color
Molecular scattering isn't the whole story. When atmospheric particles are slightly larger than light wavelengths, a separate process called Mie scattering kicks in alongside Rayleigh scattering, according to the Lake Champlain Committee. Dust, water droplets, and other aerosols reflect and scatter light across the spectrum, producing the softer pastel blends of pink and pale blue often seen at dawn and dusk.
Clouds play their own role in amplifying the effect. High-altitude clouds like cirrus can catch low-angle sunlight above the denser surface boundary layer, reflecting pink, gold, and red hues down toward observers on the ground. Lower cloud layers, by contrast, often sit in haze that can mute the same effect.
Why South Florida Sees It So Often
Weather patterns can intensify the display further. High-pressure atmospheric systems induce descending air that traps surface dust, soot, and aerosols beneath a temperature inversion layer, frequently sharpening sunrise and sunset color displays, according to NOAA's Global Monitoring Laboratory. In South Florida specifically, Saharan dust plumes carried across the Atlantic by easterly trade winds regularly reach the region between late June and mid-August, suppressing widespread thunderstorm activity while enhancing vivid sunrise and sunset colors, per Venice Florida's Friendly Weather Service.
Winter sunsets can be more brilliant when humidity and smog are lower. As for why the clear daytime sky reads as blue rather than violet — even though violet light scatters more efficiently — our eyes are more sensitive to blue light, per NWS Flagstaff.
NWS Miami Explains the Sunrise
NWS Miami used its X account to share an educational explanation of the sunrise glow.
