Download Weather Maps - San Francisco State University

22
INFORMATION DESIGN INDEX CARDS
Weather Maps
T
Weather maps may take on a variety of
forms depending on the amount of data
needed to be visualized by the viewer.
Therefore, while meteorologists may
need multiple levels of data to be plotted
onto a map, laypersons generally appreciate forms that contain less information
Association of American Geographers
he process of surface weather analysis involves gathering large
quantities of data and compiling it into a visual representation in
order to illustrate the weather conditions of a specific area. The result is
a graphical model commonly referred to as a weather map.
and are easier to read.
Surface maps are used to depict largescale elements of the weather, and are
Fig. B: Close-up of the first known weather map
as drawn by Edmond Halley in 1685.
helpful in predicting weather patterns.
These elements include high and low
Origins
pressure systems, cold and warm fronts,
The first known weather map was
and precipitation areas. You may often
published in 1686 by Edmond Halley.
find surface maps in use on television
The paper, published in Philosophical
news programs.
Transactions, attempted to provide a
weather.com
historical view of trade winds observed
around that time.
Albeit inaccurate, this milestone effort
established cartographic methods that
would later influence pioneer meteorologists almost two centuries later. It wasn’t
until 1837 that wide-scale weather infor-
er
.o
u.
through the invention of the telegraph.
th
ea
mation gathering was made possible
w
ed
Fig. A: Surface weather maps provide an
overview of weather activity during a specific
period of time.
Fig. C: A surface
weather chart with
raw data; commonly
used by meteorologists
to analyze weather
patterns.
u
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What Does it Mean?
wfmz.com
Pressure Systems
High
Cold Fronts
Warm Fronts
Low
Warm
Warm
Cold
H
Cold
L
Fig. D: High pressure converges air downwards,
while Low pressure diverges air upwards.
Fig. E: A side view of cold front activity. These
can move up to twice as fast as warm fronts.
Fig. F: A side view of warm front activity–typically
less common than cold front activity.
High Pressure System An area of
A Cold Front is the leading edge of an
A Warm Front is the leading edge of an
relative pressure maximum that has
advancing cold air mass that is under
advancing warm air mass that is replac-
diverging winds and a rotation opposite
running and displacing the warmer air in
ing a retreating cold air mass. Generally,
to the earth’s rotation. Fair weather is
its path. Generally, the temperature and
the temperature and humidity increase,
typically associated with high pressure.
humidity decrease, the pressure rises,
the pressure rises, and the wind shifts.
and the wind shifts.
Low Pressure System An area of relative
Precipitation, in the form of rain, snow,
pressure minimum that has converging
A narrow band of precipitation is gener-
or drizzle, is generally found ahead of
winds and rotates in the same direction
ally at or behind the front, and with a
the surface front, as well as showers and
as the earth. Stormy weather is
fast-moving system, a squall line may
thunderstorms. Fog is also common in the
associated with low pressure.
develop ahead of the front.
cold air ahead of the warm front.
Front System
Warm
Cold
Precipitation
Rain
Drizzle
Thunderstorm
Sleet
Cloud Cover
Clear Sky
1/8ths
5/8ths
6/8ths
Sources
An Introduction to Weather Map Symbols and
Terminology, by Rachelle Oblack
www.about.com
Atmospheric Circulation: Weather Systems
www.nasa.gov
Edmond Halley as a Thematic Geo-Cartographer,
by Norman J. W. Thrower
www.jstor.org
History of Surface Weather Analysis
www.wikipedia.org
Occluded
Snow
Snow Shower
2/8ths
7/8ths
Stationary
Hail
Mist
3/8ths
Overcast
How to Read a Surface Map
www.weather.com
National Weather Service
www.noaa.gov
What is the Difference Between a Low Pressure
and a High Pressure System?
www.wfmz.com
Trough Line
Shower
Fog
4/8ths
Obscured
Fig. G: Weather symbols commonly used in surface analysis charts.
Information Design Index Cards is a set of cards designed and produced by the
students of DAI 523, Information Design 1, a fourth-year course in the Design
and Industry Department, San Francisco State University, Fall 2009. The set, by
no means complete, is composed of 1+22 cards on Information Design topics.
Coordinated by instructor Pino Trogu, each topic was chosen and researched
by the students. DAI 523 provides students with an introduction to the field
of information design, covering a variety of applications across print, screen
and environmental media. This is card number 22 and it was designed by
Eugene Wong.
523_prj02-4.indd 2
DAI 523
Information Design I
Design and Industry Department
College of Creative Arts
San Francisco State University
California, USA – October 2009
Information Design Index Card
No.22
Printed by JASK Digital Printing
11/2/2009 2:03:58 PM