Chapter 1
Ways of Seeing
Ways of Seeing the
Atmosphere
• The behavior of the atmosphere is very
complex.
• Different ways of displaying the
characteristics of the atmosphere and
its behavior helps us see a complex
situation in its more simpler aspects.
• We will review 7 fundamentally different
ways of seeing the atmosphere as used
today by meteorologists.
Graphs
• In meteorology, graphs typically display
some atmospheric parameter as a
function of one of the four dimensions
(x, y, z, time).
• (1) Meteogram displays parameters as
a function of time.
– A common graph used to display
observations at a location over time, or
forecasts at a location over future time.
•
•
•
•
•
•
•
•
Notice pressure peaks at
16:00 GMT.
Also, secondary peak at
~04:00 GMT.
About 12 hours apart.
Due to semi-diurnal tide
in atmosphere - heating
by Sun and cooling at
night.
Wind Speed/Gusts/Dir
Mentions wind direction
shifting from 360o to 0o.
Is this a truly significant
wind shift?
What about shifting from
360o to 180o
• (2) Sounding Diagram
(Thermodynamic Diagram)
– Represents characteristics of atmosphere
(pressure, temperature, moisture) vertically
through the troposphere above a particular
location.
– Depiction is opposite to a normal graph:
the independent axis is the vertical axis
and the dependent axis is the horizontal
axis.
– On this particular diagram, the temperature
lines are skewed to the right.
• Will cover in more detail
later.
• Winds at various levels
are plotted along the right.
• Diagram to upper left is a
hodogram, showing
behavior of balloon
moving with the wind.
• (3) Isopleths - (An analysis)
– Show a parameter as a function of two
dimensions, usually x and y.
– Help to delineate the field of a particular
parameter being analyzed.
– Each line represents a particular value of
that parameter.
– Aids in determining parameter values
between the isopleth lines.
– Often, the measured (or calculated) values
Both maps are for the
same time using the
same data.
Values between isopleth
lines can be determined
by estimation.
The color filled map aids
in showing regions of
maximum and minimum
values.
• To estimate, do a
linear interpolation, divide the space
between the isopleth
lines into an equal
number of
subsegments.
• (4) Plotted Data
– Plotting data on an observational map is
usually the first step before an analysis
(drawing isopleths) is done.
– The user can see the data.
– The data may contain errors since
measurements may contain errors, errors
resulting from transmission of data, errors
from plotting data.
– Some maps may contain only one
parameter, others may contain several.
– There is a standard format for plotting
surface and upper-air observational data.
Example Single Parameter map.
– May be preferable
when observations
are insufficient to
indicate the proper
shape of the
contours.
– May be preferable
when the parameter
does not smoothly
transition between
isopleth values; e.g.,
rain showers.
(5) Images
• Typically used for Radar and Satellite
data.
• Two-dimensional (x, y) plots.
• Satellite data resolution (~1 km) much
closer than surface observations.
• Images may be colorized and give a
depiction much like an color-filled,
analyzed map.
– Satellite images are typically:
• Visible Satellite Image
• Infrared Satellite Images
• Water Vapor Images
Other data:
-Temperature
profiles.
- Moisture profiles.
-Wind direction and
speed.
– Radar Images
• Provide very detailed information on
precipitation, more than can be obtained from
point-source measurements.
• May contain “noise.” Return from nonprecipitation objects; insects, birds.
• Radar measures the intensity of the returning
radar signal. Then uses an algorithm to
determine precipitation.
• Display is very similar to a color-filled analysis.
• Sometimes, if you are only interested in the
large scale phenomena, too much detail can be
a hindrance.
• (6) Visualizations
– Representations of data that retain visual
cues for the three-dimensional variation of
the data field.
– Animations.
– RUC maps.
• (7) Equations
– An equation describes how, in a mathematically precise
way, different parameters relate to each other.
– In meteorology, they represent the behavior of the
atmosphere.
– Equations are timeless. It applies at any time and at
any given point in the atmosphere.
– One should learn to visualize the equation expressing
how the atmosphere behaves and the relationship
between the elements of the equation.
– With an analysis (which shows the state of the
atmosphere at a particular time) and a proper equation,
one has a way of predicting the state of the atmosphere
at a future time.
• (8) Conceptual Model
– Helps meteorologist understand a complex, 3dimensional atmosphere and how it evolves by
simple models - even though the model is a
generalization.
• Mid-latitude cyclones with attendant fronts.
• 3-Cell model of the atmosphere.
– A meteorologist can take the current weather situation
and fits well-understood weather systems to it.
Recognizing that the model will not be an exact
representation of the current weather situation.
– Ultimately, learning about the atmosphere largely
consists of conceptual model building.
– If a conceptual model does not apply exactly, the
forecaster should know how those differences between
the conceptual model and the real atmosphere will
affect what the atmosphere does.
– Analog forecasting is an example of using a conceptual
model to forecast.
• Chapter 1 Questions
– Do: 1, 2, 3, 5, 6.