Name: ____________________
Date: __________
Regents Earth Science
Period: _____
Lab # 38 Large-Scale Atmospheric Fields
Objectives:
Earlier this year you used the concept of the field as a way of describing the pattern of variation of
some factor over a given region. A synoptic weather map is a map on which the field of several weather
variables is plotted for a given time over a large area. Such maps are used to predict future atmospheric
conditions. In this investigation you will use the field concept in mapping large-scale patterns of variation
in the earth's atmosphere.
Problem: How can you interpret weather variables with the use of a synoptic weather map? Objectives:
After you have completed this investigation, you should be able to:
1.
Plot the data of a number of atmospheric variables on a weather map.
2.
Construct isolines to form a field diagram of a number of weather variables.
3.
Use the field diagrams to identify areas of high and low barometric pressure, air temperature,
weather fronts and precipitation.
PROCEDURE
The symbols on the weather map on page 3 are derived from reports of various weather stations. As
explained in the map key, they give information on air pressure, temperature, wind direction,
precipitation, and cloud cover. Use this information to prepare four maps of the fields of these
conditions on pages 3-6. Draw isolines and use shading as indicated in the instructions given below for
individual maps:
(a)
Label Map A Barometric Pressure Patterns. Using a pencil, draw isolines between stations to
show barometric pressure (isobars). Use a 4-millibar interval between lines starting with 1004.0 millibar
line (which would be shown on the map as 040). This isobar will form a closed loop around a low-pressure
center. Label the center of this first loop with a capital L. Continue until you get to the high-pressure
center. Label this with a capital H.
(b)
Label Map B Surface Wind Patterns. Draw a short arrow through each circle indicating the
direction of wind movement at that city. Draw stream-lines (longer arrows representing the direction air
would move) for the general map area.
(c)
Label Map C Surface Temperature Patterns. Lightly sketch (in pencil) equal-temperature lines
(isotherms) starting with the 30° isotherm using a 10-degree interval between lines. When you are
satisfied that the lines are correct, darken them with pencil or ink. The lines should follow the measured
temperatures with a minimum of variation based on guessing. Irregularities should not be smoothed out!
(d)
Label Map D Sky Conditions and Precipitation Patterns. Draw a boundary line enclosing the
partly cloudy area and draw vertical lines throughout the area to distinguish it from surrounding areas.
Draw a line enclosing the cloudy or foggy area and crosshatch this entire area to distinguish it. Draw a
line enclosing the area where it is raining. Shade this area with your pencil to distinguish it from the
others.
Examine the four maps carefully and compare them to each other. Write a brief description of the
patterns that you observe on each map. Answer the questions on page 2.
1
Analysis: Write a brief description of patterns that you observe on each map
Map A: _______________________________________________________________________
____________________________________________________________________________
Map B: _______________________________________________________________________
____________________________________________________________________________
Map C: _______________________________________________________________________
____________________________________________________________________________
Map D: _______________________________________________________________________
____________________________________________________________________________
Questions:
1. Where is the high pressure system located? ____________________________________
2. Which way is the wind blowing in this part of the US? (toward) or (away) [circle one]
3. What is the circulation pattern? (clockwise) or (counterclockwise) [circle one]
4. Where is the low pressure system located? _____________________________________
5. Which way is the wind blowing in this part of the US? (toward) or (away) [circle one]
6. What is the circulation pattern? (clockwise) or (counterclockwise) [circle one]
7. Where do you get precipitation? Near the high pressure system or near the low pressure
system? _______________________________________________________________
8. Check your maps carefully. There are two types of weather fronts on this day. Both start in the
center of the low. Describe the location of the two fronts (Hint: the difference in temperature
on different sides of the front is approximately 15°F. Check the wind direction to figure out if
the warm or the cold air is pushing. This will tell you if it is a warm or a cold front.).
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________
9. The surface air pattern indicates air flowing toward the center of the low pressure system near
Cincinnati. Where does the air go once it gets to the center of the low?
_________________________________________________________________________
2
Map A - Title: ____________________________________
Map Key:
1004.0 mb
1008.0 mb
1012.0 mb
1016.0 mb
1020.0 mb
1024.0 mb
L =
H =
3
=
=
=
=
=
=
040 isobar
080 isobar
120 isobar
160 isobar
200 isobar
240 isobar
Map B - Title: ____________________________________
Map Key:
4
Map C - Title: ____________________________________
Map Key:
5
Map D - Title: ____________________________________
Map Key:
6