Jet Streams

This week’s topic is the effect of the jet stream on weather and, ultimately, on climate change. It is a subject this scientist knew nothing about before starting this essay but serves as a great example of how scientific method works to answer unanswered questions about the natural world. Answers are found when an individual or research team addresses one part of the puzzle and then bit by bit, builds on the work of others until a generalized understanding is achieved.

From the North Pole to the South Pole there are generally four jet streams. One hundred or so kilometre-wide bands of air current that wrap around the earth. Eleven kilometres above us at the interface of two zones in our atmosphere, the Troposphere (rough zone) and the Stratosphere (calm zone), jet streams whirl and undulate around the globe, largely in an easterly direction. They have a huge influence on the winds, weather formations, and even ocean currents far below them. When there is a change in the jet steams we down here on earth notice.

One study by R. D. Hudson, coming out of the University of Maryland’s Department of Atmospheric and Oceanic Science, showed that over the last three decades the polar jet streams North and South have moved gradually toward the equator and the sub-tropical jet streams have moved pole-ward. The study explains that changes in jet stream position lead to stream undulations becoming more erratic with entire aerial waves breaking off causing storm formations that are increasingly more powerful and destructive.

It is theorized that a generalized increase in the temperature worldwide, partially brought on by greenhouse gases such as CO2 getting trapped in the Troposphere and in turn holding heat in, is resulting in polar ice packs melting. The sun’s radiative heat that used to bounce off the ice is now being absorbed by dark ocean water. The water is heating up and moving away from the poles by currents, which in turn, heats the air above it. The unprecedented temperature increases of the atmosphere above the polar regions is causing jet streams to move in unpredictable ways and, in the process, is causing great upheaval in our weather.

Hudson and his team studied one small feature of the jet stream-weather puzzle, a means to evaluate their boundaries illuminated by differences in ozone concentrations along jet stream fronts.

Traditionally, jet streams and weather in general are tracked by a worldwide network of weather stations sending up weather balloons carrying aloft electronic recording devices that transmit readings back to earth. When the balloons pop, often at an altitude of twelve to fifteen kilometres and some two hundred kilometres away from their lift-off position, the electronics (equipped with parachutes) sometimes make it back to earth.

Using Hudson’s method of evaluating ozone from satellite scans, the study of jet streams has become much easier, less expensive and has served to greatly increase the body of information available making a clearer understanding of the causes of climate change possible. Atmospheric scientists do not yet have the complete answer but are getting closer, thanks to the work of Hudson and many other researchers.

Leave a Reply

Your email address will not be published. Required fields are marked *