Meteorology 1010 Supplement to Chapters 9-11 This PowerPoint is not a substitute for reading the textbook and taking good notes in class. This PowerPoint presentation is the first of two that supports Quiz #4, Fall Semester, 2013. P owerpoint presentations should be viewed as a study guide.
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Meteorology 1010Supplement to Chapters 9-11This PowerPoint is not a substitute for reading the textbook and taking good notes in class.
This PowerPoint presentation is the first of two that supports Quiz #4, Fall Semester, 2013.Powerpoint presentations should be viewed as a study guide.
Jet StreamsMeridionalvs Zonal FlowWhen the jet stream provokes storms by mixing cool/dry with warm/wet storminess can occur.Mid-latitude storms often begin with mixing of cool/dry air and warm/wet air as the jet stream(s) undulates more north/south, helping to mix differing air masses.
November 18 Salt Lake weather report indicated that westerly flow was going to be more ‘zonal’ rather than ‘meridional’ so there would not be any increasing intensity that otherwise might occur if ‘storm track’ flow dipped north or south to pick up greater moisture and/or greater contrast.Sunday’s tornadoes in Illinois were unusual because of more-than-normal moisture and heat – November usually exhibits snow storms, with some wind.
This one is a cold front. A warm front would have similar features, but more gradual.
Notice that the cold-frontside is more vigorous than the warm front side
Warm front chasing cool air
Cold front chasing warm air
Faster-moving cold front gradually overtakes warm air and causes warm air to lift.
Notice that the cold front side shows more severe radar returns – more vigorous lifting and more severe weather.
Relatively Cold Air
Relatively Warm Air
Notice that in a mid-latitude cyclone, cold and warm air don’t mix at first.
As Coriolis force helps turn the air, mixing begins as warm, humid air lifts over cooler, drier air that is more heavy.
Rising air provokes condensation, precipitation and strong winds.
At the end, warm air is temporarily stable above cold air below.
Here we see how the jet stream (with storm track) helps pull low and high pressure cells toward each other.
The difference between warm/wet and cool/dry
helps produce rising air, high wind, precipitation, hail, lightning.
Warm, wet air rises above cool/dry air classic “frontal” storm.
If you click quickly on the next six slides you can see how a mid-latitude cyclone can develop.
Mountainous regions, such as the Rockies and the Appalachians, experience a greater number of air-mass thunderstorms.
Because Utah is fairly dry, we have enough heat for dust devils and brief air-mass thunderstorms.
For really severe weather, heat and humidity are needed – not just “cash”, but “credit”
Warmer, more humid air
No. However, a persistent pattern of more severe weather is consistent with other findings about climate change.
Based on this chart, can we use single events to support the theory of global warming?
A November 2013 tornado reached nearly 200 mph
2013 tornado in Oklahoma probably produced 300 mph wind.
News reports stated that:“Predictions are saving lives.”The truth is - - they weren’t genuine predictions, just better quality warnings.Oddly, hurricanes are so big that we can only generalize about where, what and when - - just a forecast. Oddly also, tornadoes are so small and transient that they are very difficult to predict - - we can forecast better, but not really predict.