Skip to Main Content
U.S. Forest Service
Caring for the land and serving people

United States Department of Agriculture

Home > Search > Publication Information

  1. Share via EmailShare on FacebookShare on LinkedInShare on Twitter
    Dislike this pubLike this pub


    Smoke from wildland burning in association with fog has been implicated as a visibility hazard over roadways in the southern United States. A project began in 2002 to determine whether moisture released during the smoldering phases of southern prescribed burns could contribute to fog formation. Temperature and relative humidity measurements were taken from 27 smoldering 'smokes' during 2002 and 2003. These data were converted to a measure of the mass of water vapor present to the mass of dry air containing the vapor (smoke mixing ratio). Some smokes were dry with almost no moisture beyond ambient. Other smokes were moist with moisture excesses as large as 39 g kg-1. Calculations show that ground-level smoke moisture excesses have no impact on ambient relative humidity during the day. However, the impact at night can be large enough to increase the ambient relative humidity to 100%. Therefore smoke moisture may be a contributing factor to the location and timing of fog formation.

    Publication Notes

    • You may send email to to request a hard copy of this publication.
    • (Please specify exactly which publication you are requesting and your mailing address.)
    • We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
    • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.


    Achtemeier, Gary L. 2006. Measurement of moisture in smoldering smoke and implications for fog. International Journal of Wildland Fire, Vol. 15: 517-525


    highway accidents, visibility

    Related Search

    XML: View XML
Show More
Show Fewer
Jump to Top of Page