     Hands-On, Minds-On Meteorology
Description | Programming | Operation

 Wind Vector Diagram Description The Wind Vector Diagram program allows the user to look at how the balance of forces change the lowest 1km of the atmosphere. Forces are represented on a vector diagram. click for whole shot

Objectives

The primary objective of the Wind Vector Diagram program to give the student a visual interpretation of how friction influences wind direction and speed.

Programming

Theory

No outstanding theory. When a slider is moved or a button is pressed, functions that calculated the forces are initiated.

Assumptions

• Geostrophic wind = 25 m/s to the east.
• Surface wind = 10 m/s also to the east
• Pressure Gradient Force = constant at the value opposite the Coriolis Force when there is no friction.
• Friction always in the direction opposite of real wind (not truly the case -- see Bluestein: Synoptic Dynamic Meteorology in Midlatitudes Volume 1: Principles of Kinematics and Dynamics.)

Equations

 Equations for Wind Vector Diagram Program Ekman Wind Coriolis Force Friction (Pressure gradient force's magnitude is constant, as is Geostrophic wind.)

Other

N/A

Operation

Running the Program

• Click the link for Wind Vector.
• Change altitude above earth's surface with slider bar.
• Change surface friction with slider bar.
• Adjust hemisphere with the radio buttons for "Hemisphere": "north" and "south".
• Vectors are defined on the graphic:
• orange = pressure gradient force
• blue = Coriolis force
• red = friction force
• white = Total wind (resultant wind)
• open white arrow = geostrophic wind

Extra Knowledge

N/A Department of Atmospheric Sciences University of Illinois at Urbana Champaign Created by Dan Bramer: Last Modified 07/27/2004 send questions/comments to bramer@atmos.uiuc.edu