Download Chapter 16 Weather Maps and Isotherms/Isobars Lab

Chapter 16 Weather Maps and Isotherms/Isobars Lab
Objective:
- Correctly draw areas of temperature and pressure differences on a map.
Directions:
Map A instructions: Drawing Isotherms
Isotherms are lines on a map that connect locations that have the same temperature. Isotherm
maps show where temperatures are relatively high and low, and also where temperature changes
are gradual or dramatic over a distance. They are large black lines that are typically places 10
degrees apart.
1. Determine which 10 degree intervals will be necessary to use for this map.
2. Draw in the isotherms on the map you have printed out. Label each isotherm.
Map B Instructions: Drawing Isobars
Certain weather maps allow us to view High and Low pressure systems that control the weather.
An isobar is a line connecting locations of equal barometric pressure. Isobar maps show where
pressures are relatively high and low, and show us where pressure changes are gradual or
dramatic over a distance over a distance. The lines are typically 4mb apart.
1. Determine which 4 millibar intervals will be necessary to use for this map. (Keep in mind
that the isobars are found every 4 millibars such as 996, 1000, 1004, etc.)
2. Draw in the isobars on the map you have printed out. Start with the 1000 mb line, then
adding 996 mb, 1004 mb, etc. Label each isobar. Note: isobars form sets of curves that do
not cross each other.
Isobars can be used to identify “Highs” and “Lows”. The pressure in a high is greater than the
surrounding air. The pressure in a low is lower than the surrounding air.
3. Label with an “H” the center of a high pressure area.
4. Label with an “L” the center of a low pressure area.
High pressure regions are usually associated with dry weather because as the air sinks it warms
and the moisture evaporates. Low pressure regions usually bring precipitation because when the
air rises it cools and the water vapor condenses.
Analysis Questions on back side.
Analysis Questions (complete sentences):
Looking at Map A:
1. Compare temperature changes as you go inland from the west and east coast, which one
has the most dramatic in temperature? Why do think this is?
2. Summarize what this picture shows us about temperature.
Looking at Map B:
The strength of the wind is determined by changes in the pressure gradient. A large change in
pressure over a short distance would indicate strong winds. On a weather map, isobars that
are close together indicate a strong pressure gradient.
Imagine that you live in El Paso, Tx.
3. If a high pressure system were approaching you from the west, describe the shift in wind
direction as the high approaches you and then passes to the east.
4. How would pressure measurements change as the High approaches and then passes to the
east?
Imagine that you live in New York City
5. If a low pressure system were approaching you from the west, describe the shift in wind
direction as the Low approaches you and then passes to the east.
6. Indicate on your map where you expect the strongest winds by drawing “x's”. (the
steepest pressure gradient.)
Map B
Map A