Metr 356

SEPTEMBER 13, 2004 NOTES

Michelle Cristofani and Tristen Stickel

Assignments:

Homework Assignment #1 due Friday 9/24

Reading: nothing new

Homework:

Homework Assignment #1 can be found on the class website. It is due Friday September 24.

Housekeeping:

We began the class by looking at a current weather map. On this map we discussed temperature and relative humidity between different cities and locations around the continental US. Z time was discussed.  12Z=8 a.m Eastern Pacific.  12-7=5 pacific time +3 for Eastern Time.  The larger the difference between temperature and dew point the lower the humidity.  A temp of 62 and a dew point of 62 = 100 percent humidity. The dew point roughly =the water vapor present. The dew point roughly = sea surface temperature. The Gulf of Mexico and Western Atlantic Oceans are warmer that the Pacific.

We also discussed new weather symbols. Present weather symbols are mostly used for aviation hazards. A circle with an X in the center means that the station is reporting skies that are obscured. A line down the center of a circle means that there are scattered clouds. A dash = fog.  A sideways eight = haze. Filled in circles = overcast.   Double circle = calm no wind speed.

We then looked at the Tropical Cyclone page to discuss Hurricane Ivan.

By looking at Hurricane Ivan we learned that hurricanes need sea surface temperatures of at least 82 degrees, less than that and they reduce. Hurricanes can get as far north as San Diego, but they die quickly as sea surface temp gets below 82.

The class continued with a discussion on pressure and wind. Generally, south winds are warm(from the equator) and north winds are cold(from the poles)Dew point temperatures above 60 usually come from warm ocean winds. And then we looked at how pressure was plotted on the weather station model. The three-digit number that accompanies dew point and temperature stands for pressure. To decode this three-digit number you place a number 9 or 10 in front of the three-digit number. The pressure should be anywhere from 960 to 1050 mb. Place a 9 or 10 when appropriate for this scale. Place a decimal before the last three-digit number and place the units (millibars. This will give you the exact pressure. The atmosphere has weight and pressure is the measurement.  The atmosphere has a top, a midpoint, and a bottom(surface)
The atmosphere stops at about 450 miles up.
1,000 millibars= surface pressure.  500 milibars = middle.

There are four different levels of intensity that the weather service uses to describe rain, wind, and snow.
The difference between rain and drizzle is the size of the droplets.  .33 inch per hour=heavy continuious rain.