Contrails not Chemtrails

  1. Spreading Contrail Examples.
  2. New Contrail Studies.
  3. Search for contrails in satellite imagery.
  4. Clouds and Contrails in Motion.
  5. Link to a radio talk show where Dr. Minnis provides answers to questions about contrails and "chemtrails." It was recorded on March 19, 2006 starting at 10 AM as part of the "Talk of the Bay" show at KUSP public radio in SantaCruz, California.
  6. Link to the NOVA article, "The Contrail Effect" by Peter Tyson
  7. Jet Trails just water vapor, not sprayed chemicals, experts say : November 29, 2006 article, by Anne Paine
  8. Concern Grows Over Pollution from Jets : December 19, 2006 USA Today article, by Gary Stoller.
  9. Langley Researcher Takes Conspiracy Out of Contrails in USA Today, February 22, 2007.

Spreading contrail examples

1977: DMSP thermal-IR image showing contrail spreading, diffusion, and thinning, DeGrand et al.(2000).

DeGrand, J. Q., A. M. Carleton, D. J. Travis, and P. J. Lamb, 2000: A satellite-based climatic description of jet aircraft contrails and associations with atmospheric conditions, 1977-79. J. Appl. Meteorol., 39, 1434-1459.

1987: AVHRR image showing a contrail outbreak over the midwest, Travis et al. (1997).

Travis, D. J., A. M. Carleton, and S. A. Changnon, 1997: An empirical model to predict widespread occurrences of contrails.  J. Appl. Meteorol., 39, 1211-1220.

1994: Pseudo-color, multispectral AVHRR images taken April 20, 1994 at 1430 UTC, and 2230 UTC, from NOAA-12 and NOAA-14, respectively, reveals a considerable number of contrails over Oklahoma, Kansas, and adjacent areas.

1995: Pseudo-color, multispectral image constructed from November 20, 1995 1-km resolution AVHRR data over NASA Langley in southeastern Virginia near 1430 Local Time, reveal a wide-ranging network of contrails both in and out of ambient cirrus clouds over much of the mid-Atlantic coast.

1996: October 26 GOES-8 images showing obliteration of Kansas by contrail cirrus. GOES-9 and NOAA-12 images from May 12-13 showing a NASA DC-8 racetrack contrail, Minnis et al. (1998).

Minnis, P., D. F. Young, L. Nguyen, D. P. Garber, W. L. Smith, Jr., and R. Palikonda, 1998: Transformation of contrails into cirrus during SUCCESS. Geophys. Res. Lett., 25, 1157-1160.

2001: November 13th NOAA-15 AVHRR infrared over the Southeast showing contrails of various ages. Terra MODIS true color image over the Midwest also showing aging contrails, Palikonda et al, (2005).

Palikonda, R., P. Minnis, D. P. Duda, and H. Mannstein, 2005: Contrail coverage derived from 2001 AVHRR data over the continental United States of America and surrounding areas. Meteorol. Z., 14, 525-536. (For a reprint, please contact

2002: Under certain conditions contrails persist for long periods of time and can extend  over great distances as seen in this August 13 (1056 UTC)  NOAA-16 4-km AVHRR image over the Pacific.  The contrails and cirrus clouds can be seen in the IR image (lower panel) but the visibility is greatly enhanced by the use of an IR temperature difference image (upper panel), Minnis et al. (2005).

Minnis, P., R. Palikonda, B. J. Walter, J. K. Ayers, and H. Mannstein, 2005: Contrail properties over the eastern North Pacific from AVHRR data. Meteorol. Z., 14, 515-523. (For a reprint, please contact

2004: NOAA-17 satellite images taken during the morning of March 20, 2004 over the Pacific  Northwest show how a contrail outbreak can appear to be regular cloud cover but is, in fact, mostly spreading contrails.  The image on the left is a standard infrared satellite image, while that on the right uses two infrared wavelengths to reveal contrails.

2007: NOAA-17 satellite image taken at 16:00 GMT of March 6, 2007 and MODIS TERRA satellite image taken at 16:33 GMT of March 6, 2007 show how a contrail outbreak over the South East U.S.

New Contrail Studies

Contrail formation diagrams: How short-lived and persistent contrails differ

JPG versions:  somewhat blurry (~ 800 kbytes)  English, Spanish, French

PDF versions:  clear (~ 5 MBytes) English-Spanish, English-French

Search for contrails in satellite imagery

If you would like to see if contrails were visible over your favorite area on a given day, try viewing our MODIS and AVHRR imagery.

For AVHRR data,

1) Select the day on the pull down menus at the top. GAC data provide more coverage but at lower resolution. Contrails are better seen in the HRPT data, but the spatial coverage is not as broad as the GAC.

2) After selecting the day, press "SEARCH". A map is returned with orbit lines for each satellite carrying the AVHRR instrument. Pick out the satellite and orbit time you wish to see. All times are given in UTC or GMT.  To find local time, subtract X hours from the UTC time. X = west longitude / 15. If you get a negative number, add 24.

    Example: Say you want central Oklahoma (longitude is about 97 deg West)
        UTC = 13:58, X = 97/15 = 6.5 or 6:30.
        LT = UTC - X = 13:58 - 6:30 = 7:28.
        If daylight savings time, add one hour to LT.

LT is an approximation to your actual local time because time zones are very broad. Use this LT cautiously.  It should get you to within 1 hour of your desired time in daylight or standard time.

3) Select the desired satellite on left sidebar. Another map appears giving the orbits only for the selected satellite. On the left sidebar, the times are listed those images that are actually available on our server.  (If you cannot find them in the HRPT imagery, try the GAC images if you are really interested.)

4) Click on the desired time (if no times are displayed, you will need to try another satellite or GAC data). The infrared (chan 4 gray) image is displayed with a map overlay.

5) Scroll around to see if the area you need is in the image. You can view the image in false color by clicking on RGB 1,3-4,4 or RGB 1,4,3-4 (NOAA-17 has RGB 1,6,4). under "Channel" on the sidebar. I prefer the first RGB. You can look at a number of other channels also.

6) The best channel for "seeing" contrails is "chan 4-5". This image is produced by taking the difference between two different infrared channels. Contrails typically show up as linear features. Sometimes, their locations are very easy to discern.  Sometimes they can be confused with other features.  THerefore, it wise to look as the other images to see if they are contrails or some other feature.

7) Try this procedure for NOAA-17, 16 March 2006 at 1706 UTC. You can see a few over WY, MN, ND, WI, PA, TN, AL, MI, central TX, and the OK panhandle. But there are hundreds over AZ, UT, NM, and CO. If you look at the RGB 1,6,4 image, you can see areas covered by snow appearing as bright magenta. Low clouds are whitish or yellowish. High clouds are pinkish, or purple, or gray or sometimes white. When the sun goes down, these images do not look as good because we lose the reflected sunlight channels.

For MODIS data,

Follow the steps above, but now choose between Aqua or Terra.When you click on a time, you will see many more channels. Here, the best contrail channel is "11-12 µm". These images are not as crisp on the edges as the AVHRR images.

Clouds and Contrails in Motion

If you wish to see cloud changes over the day, we suggest using GOES data. A large variety of imagery is available for your viewing pleasure at Have a look.

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