Geography 103: Weather

Exercise 4. The 500 mb height chart

The map below shows the 500 mb heights, temperatures and winds for January 13, 2004. This was printed from the web site http://weather.unisys.com. Go to this site to find instructions for reading and interpreting this map. At this site you can also find surface data, upper level meteorological data, satellite images, radar data and forecasts for the US and Canada.

Please use the data sheet to answer the questions following.

In the title of the map “12Z” is used. What does this mean?

Where are the heights greatest - at the top (north) or the bottom (south)?

What are the values of the labeled contours? (i.e. What height contours are labeled?)

What units are these heights in?

Every other contour in height is labeled. Judging from these values what do you think the separation of adjacent height contours is? (Give units.)

For each weather station three numbers are given. Two on the left of the “dot”, one on the right. What does the number on the right tell us? What are the units (or, how should we read this)?

Mark the location of Los Angeles. What is the approximate 500 mb height for Los Angeles?

Mark the location of Seattle. What is the approximate 500 mb height for Seattle?

Mark the location of Boston. What is the approximate 500 mb height for Boston?

For each weather station three numbers are given. Two on the left of the “dot”, one on the right. What do the two numbers on the left tell us? What are the units (or, how should we read this)?

What is the approximate temperature at 500 mb in Los Angeles?

What is the approximate temperature at 500 mb in Seattle?

What is the approximate temperature at 500 mb in Boston?

Do warmer temperatures correspond to high or low heights?

Over most of the U.S. what direction is the wind at this height?

How is the direction of the wind related to the height contours?

Over which part of the U.S. is the wind strongest?