Metr 302 Spring 2004

Homework 2 Answers

Animation of Visible Imagery of Hurricane Mitch, 26 October 1998

  Questions
  1. Describe the general trajectory of Hurricane Mitch.
    (10 pts)
    The center of Mitch generally moved from east-southeast to west-northwest.
  2. Describe the sense of the cloud motion relative to the center of Mitch?
    (10 pts)

    The motion of the clouds relative to the center of Mitch was counterclockwise.

Animation of Infrared Imagery of Hurricane Mitch, 26 October 1998

  Questions
  1. Describe motion of the clouds relative to Mitch's center.
    (10 pts)

    The motion of the clouds relative to the center of Mitch was counterclockwise.
  2. In general, where are the coldest cloud tops located, relative to the center of Mitch?
    (10 pts)

    The coldest cloud tops, corresponding to the gold and light green colors on the infrared satellite animation, were generally surrounding the center (the eye) of Mitch and, hence, were generally associated with the eyewall.
  3. Where would you think that the heaviest precipitation would be occurring with respect to the center of the storm? Explain using concepts we have discussed in class.
    (10 pts)

    It can be surmised that the heaviest precipitation would be around the eyewall. The reason for this is that the coldest cloud tops are found there, and, as a first guess, one can estimate that the clouds there are cumulonimbus, which are tall (or tower high) enough into the lower atmosphere to have very cold tops..

Part 2. Hurricane Tracks

  Questions

  1. Does the trajectory you inferred for Hurricane Mitch (from question above) correspond to the general track of the year 2002 storms as shown in the images below?
    (10 pts)

    Yes, the general trajectory of Mitch was east to west and corresponds reasonably well with the average trajectory of storms in the year 2002. Specificially, storms Lili, Hanna and Isidore seemed to follow similar tracks in 2002.
  2. Describe the apparent relationship between tropical cyclone tracks and the sea-surface temperature pattern?
    (20 pts)

    The tropical cyclone tracks seem to be limited to regions of the ocean in which the ocean temperatures are quite warm, generally, greater than 82F. Many tracks ended on land, or, abruptly, where the hurricanes began to pass over colder ocean waters.

Part 3. Hurricane Definition

    Generic term for a "severe" nonfrontal synoptic-scale cyclone orginating over tropical or subtropical waters with organized convection and definite cyclonic surface wind circulation, often observable in cloud motions and features. In early stages, tropical cyclones move from east to west in the broad zone of the prevailing easterlies.

    Describe how the observations you made in the previous questions suggest that Mitch fits this definition. (20 pts)

    Although we don't know for sure at which latitude Mitch developed, at the time of the charts above it was moving northwestward and was south of 20N latitude. So this cyclone was over tropical waters.

    In addition, the motion of the clouds relative to the center of Mitch was counterclockwise, verifying the cyclonic nature of the windflow around Mitch. Finally, Mitch was generally moving from southeast to northwest. Thus, of the five distinguishing characteristics listed in the definition above (of which we have discussed three up to the time of this homework), we can note three of them in this case. Hence, Mitch fits the definition to the extent that we have discussed it.

montever@earthink.net