Hurricanes, El Niño and Global Warming

A look at Some Frequently Misunderstood Meteorological Topics

Bill Syrett


Penn State Weather Workshop for Science Educators 2004


From NASA's Earth Science Enterprise 2002 Summer Workshop

Table of Contents

Topics - First Session, Part I



The General Circulation of the Atmosphere: Tropical Emphasis

Exercise: Hurricane Frequency in the Atlantic and Eastern Pacific Basins


Topics - First Session, Part II

Global Warming - The Enhanced Greenhouse Effect

Land Use - The Urban Heat Island

Exercise: Temperature Trends



Topics - Second Session

Basic Air Pollution Meteorology

Sound Propagation in the Lower Atmosphere

Radiation: Basic Terminology



Radiation: Weather Radar and Satellite Images

Visible                              Infrared


Water Vapor

Colorized Infrared Image                              Composite Radar Image


Radiation: Global Balance vs Temperature











The General Circulation of the Atmosphere


The General Circulation: The Hurricane



Lab Exercise 1: El Niño and Hurricane Frequency

    1. For each basin, plot the number hurricanes/typhoons and tropical storms (sum of tropical storms and hurricanes) as a function of year.
    2. For all common years, compute the average number of hurricanes and tropical storms (sum of both) in each basin.
    3. On the graph of Atlantic (W. Pacific) tropical system frequency, note both the El Niño and La Niña years and compute the following…
      1. The average number of hurricanes and tropical storms (sum!) for all years
      2. The average numbers for El Niño years
      3. The average numbers for La Niña years
    4. What conclusions can you draw from the differences in frequency of tropical systems in each basin?
    5. Can you find any correlation between Atlantic (W. Pacific) tropical storm and hurricane frequency and the presence of El Niño or La Niña?


Global Warming


  • The Greenhouse Effect is a natural occurrence that keeps our planet habitable
    • - Greenhouse gases absorb IR radiation (heat) emitted by the earth's surface and then re-emit some of that radiation back to the surface- radiation that would have escaped to space. Primary naturally occurring greenhouse gases include water vapor and carbon dioxide.

  • The Enhanced Greenhouse Effect (which is commonly referred to as the "Greenhouse Effect") refers to an increase in greenhouse gases, especially carbon dioxide, due to human influences.


  • The Keeling Curve

  • The Cause

  • Global Temperature Trend

Web Source: U.K. Met Office

  • Computer Forecasts- Much uncertainty, especially concerning cloudiness
  • What should we do and who should pay?


The Urban Heat Island

  • The inner city is almost always warmer than surrounding countryside, and the difference generally increases as the population of the city increases
    • - Surface Characteristics
        ... higher heat capacity
        ... greater surface area
  • Emissions
    • - autos / factories not only air pollution, but heat given off
      - people give off heat
  • Water Cycling: rapid runoff means that less solar energy is used to evaporate water, thus reducing evaporational cooling

Web Source:


Lab Exercise 2: The Urban Heat Island

  • Historical Temperature Data

  • Procedure (use a spreadsheet program)
    1. Plot the average July temperatures for both cities, on the same graph, versus year.
    2. Do the same for January temperatures.
    3. Can you see evidence of the urban heat island, and if so is it more noticeable in winter or summer?
    4. Can you see evidence of global warming in the data?
    5. How can we tell the difference?





Virtually everything included in this write-up was produced by other hard-working individuals. I have freely taken images from various web sites and claim no responsibility (and deserve no credit) for their creation. Most images can be accessed from their original pages through the links provided. The labs were originally offered as part of the introductory meteorology course offered by Dr. Jon Nese at Penn State Hazleton.