Add Yahoo as a preferred source to see more of our stories on Google. Design by Channing Smith In astrology there are four elements that correspond to the 12 zodiac signs: air, fire, earth, and water.

An air mass is a large body of air that is uniform in its characteristics. Essentially, they’re large “blobs” of air that can span an entire continent. Air masses will have “source regions”, where ...

PHILADELPHIA (WPVI) -- With smoke blowing into the Philadelphia region from the wildfires in Canada, you may have heard a lot about the Air Quality Index or AQI. But what it is, exactly? The Air ...

The index rates how clean or polluted the air is each day. The EPA uses this measure to keep tabs on five kinds of air pollutants. The main concern from the wildfire smoke is fine particle pollution, ...