Instructions for General Use: This widget is meant to be exploratory - users can visualize a variety of variables or make composite maps of multiple variables. Through changing the thickness pattern and phase shifts and observing the resulting changes in QG omega equation terms, one can understand for what situations omega will be strongest or weakest, and why.
Step 1: Choose a Hemisphere. NH is the default here, but studying the results for SH can solidify your understanding.
Step 2: Choose a Thickness Pattern. The simplest option here is to start with the zonal thickness pattern, which implies a generic temperature change from cold in the north to warm in the south.
Once you understand what you’re seeing with the zonal pattern, you can move on to a wave-like (sinusoidal) thickness pattern, where you will also choose a phase shift. The phase shift is the difference between the thickness wave and the 500hPa geopotential height wave - 0 is when they are at the same position.
Step 3: Add overlays of “basic” variables. It is generally helpful to examine the 500hPa heights along with 1000-500hPa thickness contours as a minimum. This is where you can also turn on “interrogation points” over the map so that you can view numerical values of variables.
Step 4: Add overlays of color-shaded variables and terms that appear in the left-hand or right-hand side of the QG omega equation. Each variable in the LHS, RHS Term 1 or RHS Term 2 categories is highlighted within the equation itself. Place your mouse over one of the variables to see its position within the equation highlighted by an underline or overline.
Each variable can be added to the map as color-shading by clicking the the box to the left of its label. To see it as contoured isopleths, simply click the paint bucket to the right of its label to turn the shading off.
Color Scheme: Reds and yellows are used for positive or larger values, while purples blues and greens are used for negative or smaller values, EXCEPT in 1000hPa heights. The 1000mb heights are plotted using red for lower values (like the red “L” on a surface analysis) and blue for higher values (as seen in blue “H” on surface map).
Step 5: You can click on the “Interrogate points” to see the values of each variable that you have turned on in the right-hand side menu. Try it by turning on a variable, like 500 mb height, in the right-hand menu. Then, click on one of the interrogate points over the map - the value of the height field will display in a pop-up window. More values will appear for each variable that you have turned on.
Step 6: To help you get started with your investigations, click on the “Exercise 1” tab underneath the widget - questions and feedback are available to make sure you understand how to use the widget and know the types of investigations that will be in exercises 2 and 3.