14,                 THE HODOGRAPH SCREEN
11,
11,The hodograph screen follows a format similar to the Skew-t
11,screen. Wind and shear related information share the left
11,side of the screen with a list of options; the balance of
11,the screen is used as a workspace for viewing and editing
11,the hodograph and related storm motion.
11,
11,The hodograph workspace follows standard hodograph notation,
11,with 180 degrees at the top of the vertical axis, and 270
11,degrees along the right side of the horizontal axis.
11,Hodograph levels correspond to RAOB vertical wind levels
11,(direction/knots, MSL), in 500 meter increments.
11,
14,              FEATURES OF THE HODOGRAPH SCREEN
11,
11,
10,THE CURSOR:
11,
11,* The cursor position is displayed graphically; movement of
11,  the cursor is controlled with the mouse.
11,
11,
10,MEAN WIND:
11,
11,* The mean wind vectors from 0-3,6 km (AGL) portray density
11,  weighted mean winds. The 0-6 km mean wind is displayed
11,  graphically on the hodograph as an open circle.
11,
11,
10,POSITIVE SHEAR:
11,
11,* Positive shear (10-3 s-1) measures the component of the
11,  mean inflow shear (0-2,3 km, AGL) thought to contribute
11,  materially to updraft rotation. Positive shear is
11,  determined by dividing the cumulative length of all
11,  500 meter hodograph shear segments showing neutral or
11,  clockwise curvature by the depth of the layer.
11,
14,   SPACEBAR for more help...ESC returns to hodograph screen
14,        FEATURES OF THE HODOGRAPH SCREEN - continued
11,
10,SR HELICITY:
11,
11,* The storm-relative absolute helicity (SR HELICITY, (m/s)^2)
11,  for the 0-2,3 km layer (AGL) reflects a summation of
11,  streamwise vorticity through the layer, and measures the
11,  potential for updraft rotation. SR HELICITY is a function
11,  of both the vertical wind structure and the storm motion.
11,  It is represented by SHARP as the area bounded by the
11,  hodograph curve and the storm relative wind vectors at the
11,  top and bottom of the respective layer.
11,
11,* The initial calculation of SR HELICITY assumes a storm
11,  motion 30 degrees to the right of the 0-6 km mean wind,
11,  with 75 percent of its magnitude. This motion reflects the
11,  increased helicity encountered by a supercell deviating to
11,  the right of the mean wind.
11,
11,* SR HELICITY updates after editing the storm motion and/or
11,  the vertical wind structure.
11,
10,STORM MOTION:
11,
11,* The head of the storm motion vector is displayed on the
11,  hodograph screen as a colored dot. Initial STORM MOTION
11,  represents a right-turning supercell, and is used for
11,  calculating initial values of SR HELICITY.
11,
11,* The storm motion vector can be modified to reflect observed
11,  radar information (see EDITING STORM MOTION). Parameters
11,  that depend on storm motion (such as SR HELICITY) will
11,  update to reflect edited changes.
11,
10,CURSOR DATA:
11,
11,* Displays continuously updating values of storm motion and
11,  SR HELICITY (0-3 km) as a function of cursor position.
11,
14,    SPACEBAR for more help...ESC returns to hodograph screen
14,                       HODOGRAPH OPTIONS
11,
11,  F1 - Allows the user to define the vertical scale of the
11,       hodograph. For example, re-scaling the original 7 km
11,       presentation to 3 km enhances the resolution of the
11,       inflow layer, and is very useful in combination with
11,       option F4 (INFLOW).
11,
11,  F2 - Displays the RAOB vertical wind profile for editing or
11,       viewing. Also displays the pressure and height (AGL)
11,       of the RAOB level adjacent to a user defined cursor
11,       position. See EDITING THE HODOGRAPH for details.
11,
11,  F3 - Draws concentric rings of equal wind speed around the
11,       origin of the hodograph (useful when editing).
11,
11,  F4 - Displays the storm inflow vectors corresponding to
11,       RAOB wind levels (0-3 km, AGL). Also displays the mean
11,       storm inflow and the mean storm-streamwise inflow
11,       between the surface and 2,3 km (AGL). F4 clarifies
11,       the storm reference frame for a given environment, and
11,       provides valuable information for radar storm
11,       evaluation (e.g. storm inflow gradients).
11,
11,  F5 - Displays positive and negative helicity, positive and
11,       negative shear, and mean streamwise vorticity between
11,       the surface and 1,2,3 km (AGL). This information is
11,       often essential for assessing the rotation potential
11,       and possible storm type within a given environment.
11,
11,  F6 - Discards changes due to editing, and resets the
11,       hodograph to the original or latest archived version.
11,
11,  F7 - Displays the help screen.
11,
11,  F8 - Saves an edited hodograph; stores a modified sounding.
11,
11,  F9 - Returns to the main parameter screen.
11,
14,    SPACEBAR for more help...ESC returns to hodograph screen
14,                   EDITING STORM MOTION
11,
11,
10,MOUSE FUNCTIONS:
11,
11,
11,* The left button is used for editing. Clicking signifies
11,  pressing and quickly releasing the button. Dragging refers
11,  to pressing and holding the button while moving the cursor.
11,
11,
11,* Clicking the right button re-draws the sounding and
11,  includes any edited changes.
11,
11,
10,EDITING STORM MOTION:
11,
11,
11,* The storm motion can be modified at any time, except when
11,  option F2 is in use. If F2 has been selected, you must
11,  exit to the OPTIONS block before editing.
11,
11,
11,* To edit the storm motion, move the cursor to a desired
11,  direction and speed (using CURSOR DATA as a guide), then
11,  click the left button on the mouse. The graphical and
11,  numerical representations of storm motion will update to
11,  show the change.
11,
11,
11,* Parameters that depend on storm motion will also update
11,  to reflect edited changes.
11,
11,
11,
11,
11,
11,
11,
14,    SPACEBAR for more help...ESC returns to hodograph screen
14,                  EDITING THE HODOGRAPH
11,
10,MOUSE FUNCTIONS:
11,
11,* The left button is used for editing. Clicking signifies
11,  pressing and quickly releasing the button. Dragging refers
11,  to pressing and holding the button while moving the cursor.
11,
11,* Clicking the right button re-draws the sounding and
11,  includes any edited changes.
11,
10,EDITING
11,
11,* After selecting F2, the OPTIONS block displays the RAOB
11,  wind profile (direction/knots, MSL) in 500 meter levels,
11,  and the cursor transfers to the right side of the block.
11,  From this position, the cursor can move on a track adjacent
11,  to the wind profile. To simplify editing, the wind level
11,  next to the cursor is highlighted, along with the related
11,  point on the hodograph. In addition, CURSOR DATA becomes
11,  LEVEL DATA, and displays the RAOB level data (pressure, mb;
11,  height AGL, meters and feet) corresponding to the cursor.
11,
11,* To edit a wind level, track the cursor along the RAOB wind
11,  block until the selected level highlights. Then press and
11,  hold the left button on the mouse. The cursor will jump
11,  to the corresponding point on the hodograph, and the
11,  related wind direction/speed will highlight in LEVEL DATA.
11,  While holding the left button, drag the cursor to a desired
11,  direction/speed, using the highlighted direction/speed in
11,  LEVEL DATA as a guide. When the preferred direction/speed
11,  have been reached, release the left button. The hodograph
11,  and the corresponding RAOB wind level data will update to
11,  reflect the change. Parameters that depend on the vertical
11,  profile of horizontal winds will also update.
11,
11,* To terminate F2 (EDIT WIND), track the cursor to EXIT. Then
11,  click the left button on the mouse to return the menu.
11,
14,    SPACEBAR for more help...ESC returns to hodograph screen