Meteorology I Surface and 500 mb Map Discussion

Meteorology I

Surface and 500 mb Map Discussion

Instructions

For your initial post for the Module 5 Discussion, you will be playing the role of a meteorology professor who is preparing a series of “mini-lessons” on interpreting the surface and 500 millibar (mb) weather maps, and how the forces acting on air and the resulting atmospheric circulation is visualized on these maps.

 

Complete ALL* of the partially developed surface and 500 mb map mini-lessons below. Complete the lessons by either choosing the bolded word or filling in the blank to correctly complete the statement.  Where indicated, use the appropriate map (surface or 500 mb) below, which you will be addressing during your lessons, to illustrate or provide an example of the concept you are teaching about.

 

For Part 1 of your initial post:

 

  • Choose and post ONE of the completed lessons, for either the surface or 500 mb map, on the Module 5 Going with the Flow discussion forum. To maximize the learning value of this activity, our goal is to have all of the lessons posted by the end of our discussion.

 

  • Be sure to title your post with the title of your chosen lesson.

 

  • You do not need to include the map with your post since the maps are displayed at the top of the discussion forum.

 

For Part 2 of your initial post, formulate a few statements that address questions you anticipate that your students might have at the completion of your mini-lesson, and/or what additional information or resources you may have to provide your students to clarify their understanding. Post these statements below your lesson for Part 1.

 

There is also a require response post – instructions and criteria for the response are provided in the discussion forum.

 

*While you are only required to post ONE lesson, completing all lessons will further your learning in preparation to engage with your classmates and instructor in the discussion, and will also prepare you for future graded activities that will involve interpreting weather maps. Completing the mini-lessons successfully requires careful study of the Module 5 readings and lesson content.

 

 

Image from: NOAA Daily Weather Map page

 

Image from: NOAA Surface Analysis Archive page

 

Surface Map Lessons

 

Lesson Title: Surface Map Orientation

The surface map is considered a constant height map where, for the representation of air pressure, the height is equal to _______.

The solid contours on the surface map are lines of constant sea level pressure called _______, which are conventionally spaced ____ millibars apart, and visualize the horizontal pressure variation at sea level.  The isobars are generated from observations of pressure at the surface.

 

On the surface map shown, station models visualize surface weather at various locations, providing coded information on:

 

(list the weather elements (and their appropriate units) that are included in the station model on the surface map shown, and provide a specific URL or the appendix reference from our textbook for how to decode a surface weather station model)

 

Lesson Title:  Visualizing Pressure Gradient Force and Wind on the Surface Map

On the surface map, large / small pressure gradients are visualized by loosely / tightly packed isobars, indicating strong pressure gradient forces and high winds.

 

On the surface map shown, a relatively strong pressure gradient is observed over (describe a geographic region on the surface map where a strong pressure gradient is observed), further supported by the relatively higher wind speeds on the surface station models in that region of the map.

 

Large / small pressure gradients are visualized by loosely / tightly packed isobars, indicating relatively weak pressure gradient forces and light winds.

 

On the surface map shown, a relatively weak pressure gradient is observed over (describe a geographic region where a weak pressure gradient is observed), further supported by the relatively light winds on the surface station models in that region of the map.

 

Lesson Title:  Circulation around Highs and Lows (Northern Hemisphere)

Around surface high pressure centers (H), or anticyclones, winds circulate clockwise / counterclockwise and blow slightly inward toward / outward from the high pressure center.

 

On the surface map, a surface high pressure center is observed over (describe a geographic region where a surface high observed), and the station model surface wind barbs visualize this clockwise / counterclockwise and slightly inward / outward circulation.

 

Around surface low pressure centers (L), or cyclones, winds circulate clockwise / counterclockwise and blow slightly inward toward / outward from the low pressure center.

 

On the surface map shown, a surface low pressure center is observed over (describe a geographic region where a surface low observed), and the station model surface wind barbs visualize this clockwise / counterclockwise and slightly inward / outward circulation.

 

Lesson Title: Atmospheric Forces and Surface Wind (Northern Hemisphere)

The atmospheric pressure gradient force is always directed from higher / lower pressure toward higher / lower pressure, and is the force that initiates air movement.

 

Once air begins to move, the _______ Force deflects it to the right of its intended path in the Northern Hemisphere. Considering only these two forces, wind would blow perpendicular / parallel to isobars.

 

However, near the earth’s surface, the interaction between air and the terrain creates a ________ force between the air and the ground, causing the wind to blow across the isobars at an angle of around ______ degrees from higher towards lower pressure.

 

On the surface map shown, this cross-isobar flow is clearly observed over (describe a geographic region where cross-isobar flow is clearly observed).

 

500 mb Map Lessons

 

Lesson Title:  500 mb map orientation

The 500 mb map is considered an isobaric map, meaning that everywhere on the map, the pressure is equal to _______.

 

The solid contours on the 500 mb map are called isoheights, lines of constant _______ (in tens of meters) of the 500 mb pressure surface above sea level. The isoheights on the 500 mb map are observed to be in the 5000 meter (18,000 feet) range. The contours are generated from upper air sounding data.

 

Dashed lines on the 500 mb indicate lines of constant ________, called isotherms, the values of which are generally increasing / decreasing going northward.

 

The barbs on the 500 mb map indicate the wind ____ and ____ , also determined from upper air sounding data.

 

Lesson Title: Topography of the Atmosphere at 500 mb

The 500 mb map is really a topographic map of the 500 mb pressure surface in the atmosphere, with the solid contours (isoheights) indicating the height of the pressure surface.

 

Because air density depends on temperature, the height of the 500 mb pressure surface will be lower / higher in warmer, less dense air and lower / higher in colder, more dense air.

 

Therefore, on the 500 mb map, where the temperature gradient is relatively large / small (i.e., a tight spacing of the isotherms), the slope of the pressure surface is also relatively large / small, indicated by a relatively large height gradient (i.e., a tight spacing of the isoheights). A relatively large height gradient equates to a relatively strong horizontal _______ gradient, and thus relatively strong winds.

 

On the 500 mb map shown, a relatively large gradient in both the temperature and the height of the 500 mb surface is observed over (describe a geographic region where a large temperature and height gradient exists), further supported by the higher observed wind speeds on the station models in that area.

 

Lesson Title: Zonal and Meridional Flow

Zonal flow describes wind flow oriented in a mainly east-west / north-south direction.

 

On the 500 mb map shown, zonal flow is observed over (describe a geographic region where zonal flow is observed).

 

Meridional flow describes wind flow oriented in a more east-west / north-south direction.

 

On the 500 mb map shown, meridional flow is observed over (describe a geographic region where meridional flow is observed).

 

Lesson Title: Ridges and Troughs

In the upper atmosphere, wind flow is generally from west-to-east due to the generally south-to-north temperature gradient, but storms and the advection of warm and cold air masses often create east-west variation in air mass temperature, resulting in wave-like patterns in the height and temperature fields on upper level maps.

 

A region of relatively warmer / colder air in the east-west direction is indicated by a region of relatively higher / lower heights, describes as a ridge.

 

On the 500 mb map shown, a ridge is observed over (describe the geographic region where a ridge observed).

 

A region of relatively warmer / colder air in the east-west direction is indicated by a region of relatively higher / lower heights, describes as a trough.

 

On the 500 mb map shown, a trough is observed over (describe the geographic region where a trough is observed).

 

Lesson Title: Geostrophic and Gradient Wind

The atmospheric ________ force is always directed from higher / lower pressure toward higher / lower pressure, and is the force that initiates air movement. Once air begins to move, the _______ Force deflects air to the right of its intended path in the Northern Hemisphere.

 

At the 500 mb level of the atmosphere, air is above the level of frictional influence, and so the _______ and _______ forces are the only atmospheric forces acting on air. Together, these two forces cause the wind to blow parallel to / across height contours, visualized by the orientation of wind barbs and height contours on the 500 mb map.

 

A geostrophic wind describes straight flow above the level of frictional influence, where the _____ and _____ forces are balanced, keeping the air moving in a straight path.

 

On the 500 mb map shown, geostrophic wind is observed over (describe a geographic region where geostrophic wind is observed).

 

A gradient wind describes curved flow above the level of frictional influence, where the ____ and ____ forces are imbalanced, forcing the air to move in a curved path.

On the 500 mb map, gradient wind flow is observed over (describe a geographic region where gradient wind is observed).