Why is it so hazy?
Because the air is full of tiny particles (smoke, dust, sea salt or pollution) that scatter sunlight and wash the sky out to white or orange. Humid air makes haze thicker, because many of those particles soak up water and swell.
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What you're actually seeing
A clean sky is blue because air molecules scatter blue light more than red. Particles are much bigger than air molecules and scatter all colors more evenly, so the sky turns milky white and distant hills fade. Very dense smoke absorbs and scatters so much blue light that only orange and red get through, which is why wildfire smoke can turn the sun a deep red and the daytime sky orange.
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Where the particles come from
- Wildfire smoke can ride the wind for thousands of miles. In June 2023, smoke from fires in Quebec turned the sky orange over New York City.
- Dust blows off dry land in strong winds, from desert dust storms to fine dust from Africa that reaches the Caribbean and Florida in summer.
- Sea salt and spray make coastal skies hazy, especially with an onshore breeze.
- Pollution from traffic and industry builds up under a warm lid of air (an inversion) on calm days.
Haze and your air's path
Haze usually travels: if your air passed over a fire, a desert or a city a day or two ago, it carries those particles to you. Air Story's trail map shows where your air has been. For health decisions, check the official Air Quality Index for your area at airnow.gov.
Questions people ask
- Is haze the same as fog?
- No. Fog is water droplets from air cooled to its dew point. Haze is dry or slightly damp particles, and it doesn't go away when the air warms up.
- Why is the sun red when it's smoky?
- Smoke particles scatter and absorb blue and green light, so mostly red and orange light makes it through to you.