Weather Maps Exercise

: This exercise was originally created by Dr. Marion Alcorn,
at Texas A&M's Department of Atmospheric Sciences

This is a hands-on laboratory exercise and offers you a chance to learn how to interpret surface weather maps and upper air maps. There are 14 problems to be completed. If you would like to complete this exercise and have it graded by a meteorologist with the National Weather Service, simply mail your answer sheet (along with the required attachments) to:

Herron/Massie
National Weather Service Forecast Office
500 Weather Station Road
Old Hickory, TN 37138

Now, have fun! and let's analyze some weather maps!

Introduction

In order to be able to predict the conditions of the atmosphere, the "weather," a meteorologist must first understand what is producing the current weather conditions. The meteorologist does this by obtaining a "picture" of the atmosphere based on the value of certain weather elements. The elements used to describe the condition of the atmosphere are: air temperature at various levels up through the atmosphere; wind speed and direction at various levels; moisture content; presence of clouds, their type and altitude; whether it is raining, snowing, foggy, hazy, etc.

To get the best "picture" of the atmosphere at a particular time, information on various weather elements needs to be collected from as much of the atmosphere surrounding the whole earth as possible. Thus, tremendous amounts of data must be considered by a meteorologist when looking at the "picture" of the atmosphere. One way to display this data in an easy to understand format is to depict the distribution of the elements on maps, charts and diagrams. The objective of the use of these in meteorology is to represent the state of the atmosphere as a function of space, either at fixed intervals of time or at varying intervals of time. A three-dimensional representation drawn to scale would be the most accurate and natural form, but it would present numerous difficulties in plotting the weather elements at their proper location, and in interpreting the information.

That part of the atmosphere with which meteorologists are most directly concerned is a thin spherical shell with lateral dimensions thousands of times its vertical depth. The United States measures roughly 13,860,000 feet from the east coast to the west coast along latitude 39N. The troposphere, the lowest layer of the atmosphere in which the greatest amount of "weather" occurs is, on the average, 11 kilometers (7 miles or 36,960 feet) thick. To depict the atmosphere over the United States in a three dimensional representation drawn to scale in which the horizontal length was 2 feet would require a vertical distance of only 0.00534 feet (0.064 inches). Not very practical!

Either

The vertical distance must be greatly exaggerated in relation to the horizontal distance, or

a series of maps must be used, each of which represents conditions at a particular height or element: such as a pressure surface. These are what weather maps are used for.

Maps refer to a representation, usually on a flat, horizontal surface of the whole or part of an area; or a representation of a sphere or part of it. The term chart is defined as an outline map representing something in its geographical aspects. Not much difference! The term "map" is more commonly used to refer to land areas (as a road map) and the term "chart" is used to refer to oceanic areas (as a navigational chart). Meteorologists normally use the term "map" to refer to horizontal depictions regardless of whether the surface is continental, oceanic, or some level above the surface.

A "diagram" is defined as a line drawing made for mathematical or scientific purposes; a graphic design that explains rather than represents. Graphs typically are used to relate one element to another, or several other elements, or an element to altitude.

Typically a chart or map displays information in the horizontal direction; north-south and east-west, like a road map which shows you where to go.

Maps

Maps in meteorology are used to display the element characteristics of the atmosphere, as measured by individual stations, such that the stations are in the proper horizontal relationship to each other. The map then provides a means to analyze the measured elements so the meteorologist can understand the "picture" of the atmosphere.

Click here for an example of a surface weather map, showing the southern and central Great Plains.

This image shows the condition of the atmosphere as measured at or viewed from near ground level by a weather observer.

The circles represent the location of stations at which weather observers are measuring the elements of the atmosphere; temperature, humidity, wind speed, wind direction, etc.

The air temperature value measured at these stations are plotted to the upper-left of the station circle. For most of the world, the standard is to plot temperatures to the nearest tenth of a degree Celsius. In the United States, the National Weather Service plots temperature for its surface maps to the nearest whole degree Fahrenheit. The dew point is plotted, in degrees Fahrenheit, to the lower-left of the station circle.

The three-letter station identifier is plotted to the lower right of the station circle.

Here's an example of a station plot, and how to interpret it:

For another example of a station plot go Here .

At the upper-right of the map is the date and time that the weather elements were observed. The time is listed in Universal Coordinated Time (UTC), which is also sometimes called Greenwich Mean Time (GMT) and which is also identified by the letter Z. This time is given according to a 24-hour clock and is the "local time" at Greenwich, England. Thus, 18Z means 1800Z, which means 6:00 p.m. in Greenwich, England.

Click here for a world time zone map from U.S. Naval Observatory. As you can see from the table below, and this image, the local time in Texas (Central Standard Time) is 6 hours behind the local time in Greenwich, England, (UTC), unless Texas is on Daylight Saving Time, during which period the local time in Texas is only 5 hours behind Greenwich, England.

Table 1. Time Conversions
UTC to Local (standard) time	Local (standard) time to UTC
UTC - 5 = Eastern	Eastern + 5 = UTC
UTC - 6 = Central	Central + 6 = UTC
UTC - 7 = Mountain	Mountain + 7 = UTC
UTC - 8 = Pacific (California & western Canada)	Pacific + 8 = UTC (California & western Canada)
UTC - 9 = Alaska (Some offset from timezone longitude lines)	Alaska + 9 = UTC (Some offset from timezone longitude lines) + 9 = UTC
UTC - 10 = Hawaii-Aleutians (Some offset from timezone longitude lines)	Hawaii-Aleutians + 10 = UTC (Some offset from timezone longitude lines)
NOTE: During Daylight Saving Time, subtract 1 less hour from the left column and add one less hour to the right column

To check the current time in certain time zones Click Here (NOTE: To see the animated clock at this website, be sure that Java is enabled on your browser. Otherwise, to see the time represented by a static clock, be sure to click on "Disable Java Animation" in the lower left of the webpage graphic.)

Problem 1.

What is the current date and local time in the Hawaii-Aleutian Standard Time according to the US Naval Observatory Master Clock? (Note: Just click on "Hawaii Standard Time Clock," near the bottom of the page.)
Record your answer on the answer sheet. Be sure to include the Hawaii date and time, along with the corresponding UTC date and time.

Note: Naval Observatory times are based on a 24-hour clock, which runs from 00 hours to 23 hours. 00hr = midnight, 01hr = 1 am, 12 hrs = noon, 13 hrs = 1 pm, 18 hrs = 6 pm, 23 hrs = 11 pm.

Problem 2.

On the first map you opened, find the Texas panhandle. The station near the center of the panhandle is Amarillo.
What is the temperature recorded at Amarillo?
Record your answer on your answer sheet.
Be certain to use the proper units.
What is the date and time, UTC, of this map?
Record the date and time on your answer sheet.
Print a copy of your map and attach it to your answer sheet

With just the air temperature values plotted, it is hard to see any pattern to the temperature of the near-ground air across Texas. However, if this temperature field is analyzed, then a pattern emerges.

Click here for a current isotherm analysis.

This map shows an analysis of temperatures across the United States, not just for Texas. The area between the analysis lines has been colored to aid in interpretation. This map has been analyzed at an interval of 5F degrees. NOTE: The analysis lines are the dividing lines between the colors and represent specific temperature values. The scale at the left shows the temperature value occurring at the dividing line between the colors. A different isotherm map, analyzed with a contour interval of 10 degrees, can be seen by clicking here.

Problem 3.

According to the temperature analysis, where did the coldest temperatures occur in Texas at the time of this analysis?
Based on this temperature analysis, what is the date and local time in Texas, (Central Standard Time or Daylight Saving Time, whichever is appropriate for today), for this analysis?
Record your answer on your answer sheet.

Print a copy of your map and attach it to your answer sheet

The lines drawn on the map are called isolines, or isopleths, which are lines along which the value of some element is everywhere the same. NOTE: In the temperature analysis, the isolines are the dividing lines between the different colors. The map which has these isopleth lines drawn is said to be isoplethed, or more commonly, to be analyzed or sometimes contoured.

It is very important for a meteorologist, especially those involved in synoptic meteorology and weather forecasting, to see "at a glance" how the various elements vary in two- and sometimes three-dimensional space. This plotted map represents a field of the variable (or element), and can be applied to any element which has a continuous distribution in at least two dimensions. Temperature and pressure are the two most common elements in meteorology to which this is done. Having an analyzed field to interpret is much preferable to having to interpret only the numbers, as in a table, from which these fields are drawn. However, since there are many elements which may be plotted on weather maps, and analyzed by such isopleth lines, specific names are given to the various kinds of isopleths. The following gives some of the more common isopleths used on weather maps. The definitions come from the "Glossary of Meteorology" (published by the American Meteorological Society):

Isobar: A line of equal or constant pressure

Isotherm: A line of equal or constant temperature

Isodrosotherm: A line of equal or constant dewpoint

Isohyet: A line of equal or constant precipitation

Isotach: A line of equal or constant wind speed

Problem 4.
According to the temperature analysis, what is the value of the coldest isotherm drawn on the temperature analysis of the United States, Canada and Mexico? Record your answer on your answer sheet.
Be sure the time on this map is the same as the one from Problem 1. If not, print a copy of this map, attach it to your answer sheet, and be sure to reference it in your answer.

Problem 5.
What is the value of the warmest isotherm drawn on the temperature analysis of the United States, Canada and Mexico?
Record your answer on your answer sheet.
Be sure the time on this map is the same as the one from Problem 1. If not, print a copy of this map, attach it to your answer sheet, and be sure to reference it in your answer.

Rules for Drawing Isopleths

For meteorologists throughout the world to be able to understand the analyzed maps developed in other countries, there must be guidelines for analyzing data so one does not get lost in the forest of information plotted on weather maps. The procedure and guidelines for analyzing meteorological data on maps has been standardized and agreed upon by all nations which are members of the World Meteorological Organization. Following are some of these rules.

An isopleth must pass through a station if the value for the element being analyzed for that station is exactly the same as the isopleth value. On weather maps, the value of the weather elements measured at the station is plotted around a small circle which represents the station. The isopleth, thus, should pass directly through the station circle if the station value and the isopleth are exactly the same.

Isopleths can only begin or end at the edge of the map, or in a region of the map where data does not exist, otherwise they must form a closed loop. If the map covered the whole globe, and data existed for all regions across the map, all isopleths would form closed loops on the map.

Isopleths separate values which are greater than the isopleth value from values which are lower than the isopleth value. Thus, when moving along an isopleth, all values greater than the isopleth should always be on one side of the isopleth and values lower than the isopleth should be on the other side of the isopleth.

Isopleths never intersect each other or branch.

Isopleths are drawn at equal incremental values determined by the element represented and must be drawn for all values between the highest value of data plotted and the lowest value of data plotted.

When an isopleth passes between two stations, the isopleth should be drawn proportionally closer to the station whose plotted element value is closest to the value of the isopleth.

Helpful Hints for Drawing Isopleths

Copy the current surface map. Note the locations of the parameter being analyzed (perhaps, temperature?) which have lowest value and also those which have the highest value. Begin by drawing the isopleths around these centers of low or high values and gradually work outward from these centers, drawing the next higher, or lower, isopleth until the map is completed.

Sketch lightly with a soft lead pencil the orientation and spacing of the isopleths as a preliminary analysis. These Isopleths can be adjusted and darkened later. It is much easier to make corrections if an easily erasable pencil is first used.

After lightly sketching the isopleths, look for any errors and correct them. Then smooth the isopleths. Isopleths generally do not have sharp bends. However, along weather fronts, isobars often show a kink toward higher pressure as it crosses the frontal zone.

Problem 6.

On the surface map that you printed in Problem 1, you will find a field of values which represent temperatures. The temperature values are plotted to the upper-left of the station circle. Draw isotherms for every 5 degrees. Isotherms values should end in either a "0" or a "5." If possible, retrace your isotherms with a colored pencil to make them stand out.
Attach a copy of your map to your answer sheet

A Review of Plotted Data on Weather Maps

As shown on the first figure you opened, the one with weather observation data plotted for Texas, weather plotting charts are printed with a small circle at the geographic location of the major reporting stations. To recall how surface data is plotted on a weather map, refer to the graphic of the station model provided earlier on this page.

Stations are identified on the printed weather map by their assigned three-digit station number, or a three-letter identifier, next to (usually beneath) the station circle.

Meteorological data from the weather observation is plotted about the station circle in specified locations which must not be violated. If any mandatory plotted element is garbled, or partly missing, an "M" should be plotted in its place. Some data is not mandatory for reporting or plotting so if it is missing, the space for it is simply left blank and no "M" is plotted.

The following information defines the data symbols used by the National Weather Service on surface analyses, and indicates whether the data is mandatory or not.

"N," Total Amount of Cloud Cover. Represented by a darkened area in the middle of the station circle, and including conditions ranging from "no clouds" to "completely overcast."

You can also find codes for Amount of Cloud Cover in column 2 of this table. (Note: SCT= "scattered cloud cover," BKN= "broken cloud cover," OVC= "overcast cloud cover," X=sky obscured) Total amount of cloud cover is a mandatory element.

"dd," Wind Direction. Represented as a shaft extending outward from the station circle in the direction from which the wind is blowing. When plotting the wind direction shaft, imagine the top of the circle is true North and moving clockwise around the circle represents a movement from 0 degrees (at the top of the circle) through 90 degrees to the right of the circle, (which represents East) to 180 degrees at the bottom of the circle, (which represents South) to 270 degrees to the left of the circle, (which represents West) and finally to 360 degrees at the top of the circle (which represents true North). Notice that 0 degrees and 360 degrees are co-located at the top of the circle. Wind direction is not a mandatory element.

"ff," Wind Speed. Represented as barbs and/or flags extending from the wind direction shaft.

Each half barb equals 05 knots;

a full barb equals 10 knots;

each flag equals 50 knots.

Barbs and flags should extend to the left of the shaft when looking along the shaft toward the station circle. Wind speed is a mandatory element if wind direction is reported. If wind direction is given but wind speed is missing, place an X at the end of the wind direction shaft rather than an M.

Winds which are calm (reported as 000 for wind direction and 02 or less for wind speed) are identified as calm by plotting a circle about the station circle.

"TTT," Air Temperature. Although the standard for most of the world is to plot air temperature to the nearest tenth of a degree Celsius, the National Weather Service plots air temperature to the nearest whole degree Fahrenheit. Air temperature is a mandatory element.

"VV," Prevailing Visibility. In the United States, prevailing visibility is plotted in whole statute miles and/or fractions, just as it is reported. Visibility is a mandatory element.

"ww," Present Weather. A symbol is plotted which represents the type of present weather occurring. Each symbol is associated with a two-digit number which is reported in the weather observation message. Click Here for a list of symbols for present weather. Another table of Present Weather symbols can be found Here. Present weather is not a mandatory element.

"T_dT_dT_d,"Dew Point. The reported dew point is plotted in the same manner as air temperature, rounded to the nearest whole degree Fahrenheit for stations in the United States. Dew point is a mandatory element.

"C_l," type of Low level Cloud. In the weather observation report, the type of cloud is reported as just a number. The symbol associated with the reported number is plotted. Low cloud symbols (and associated code numbers) can be found in the first row of this table. The code numbers run from 9 to 1, from right to left. For instance, Code 1 refers to "Cu of fair weather, little vertical development and seemingly flattened. Code 9 refers to "Cb having a clearly fibrous (cirriform) top, often anvil-shaped. A nontechnical description of each cloud type can also be found by clicking Here. Low cloud type is not a mandatory element.

"C_m," type of Middle level Cloud. The symbol for the middle level cloud type is plotted just above the station circle and the various symbols and associated code numbers) can be found in the second row of this table. The code numbers run from 1 to 9. Code 1 indicates "Thin AS (most of cloud layer semitransparent)." Code 9 refers to "Ac of a chaotic sky, usually at different levels." A nontechnical description of each cloud type can also be found by clicking Here. Middle level cloud type is not a mandatory element.

"C_h," type of High level Cloud. The symbol for the type of high level cloud is plotted just above the middle level cloud symbol. The various symbols (and associated code numbers) can be found in the third row of this table. The code numbers run from 1 to 9. Code 1 indicates "filaments of Ci, or 'mares tails.'" Code 9 refers to "Cc alone or Cc with some Ci or Cs, but the Cc being the main cirriform cloud." A nontechnical description of each cloud type can also be found by clicking Here. High level cloud type is not a mandatory element.

"PPP," Sea-Level Pressure plotted in tens, units, and tenths of hectopascals (or millibars which is the same as a hectopascal). Sea-level pressure is a mandatory element. Sea-level pressure values generally fall between 950 and 1050 hectopascals. A pressure of 1012.5 hPa would be plotted as 125, without the decimal point. A pressure of 996.4 hPa would be plotted as 964. Since only the tens, units and tenths digits are plotted, then to decode the plotted values and obtain the actual sea-level pressure, either a 9 or a 10 must be prefixed to the plotted values and the decimal point placed between the middle and last digit of the plotted values. If prefixing a 9 to the plotted digits makes the result lower than 950.0 hectopascals, then you should prefix a 10 rather than a 9. If prefixing a 10 makes the result greater than 1050 hectopascals, then you should prefix a 9 rather than a 10. This works for most sea level pressure values.

"ppp," Amount of Pressure Change that occurred during the last three hours at the station. The tens, units and tenths of hectopascals is plotted without the decimal point. Thus, a pressure change of 02.4 hPa would be plotted as 024. The amount of pressure change is plotted in conjunction with the pressure tendency symbol and both are mandatory elements.

"a," Pressure Tendency, sometimes called the barometric trace characteristic. It shows how the pressure behaved during the past 3 hours. The symbols are numbered 0 to 8:

Notice that symbols 0 to 3 all end at a higher point than they begin. This means that the sea-level pressure is now higher than it was 3 hour ago. Notice that the symbol for number 4 is a straight line. This means the pressure is now the same as it was 3 hours ago. Note, it may have increased, then decreased, or decreased, then increased, but it is now the same as 3 hours ago. For numbers 5 to 8, the symbol ends at a point lower than it began. This means the sea-level pressure is lower than 3 hours ago. Another depiction of these sybmols can be found in the first column of this table.

When plotting the pressure tendency and amount of pressure change, the first symbol to the right of the station circle will be either a + (when using symbol 0, or 1, or 2, or 3), a blank (when using symbol 4), or a - (when using symbol 5, or 6, or 7, or 8). Next is plotted the amount of pressure change, ppp, with no decimal point. Next is plotted the pressure tendency symbol. As mentioned previously, The amount of pressure change is plotted in conjunction with the pressure tendency symbol and both are mandatory elements.

"W," Past Weather, the weather that occurred during either the past 3 hours or the past 6 hours depending on the time of the observation. Click Here for a listing of symbols for past weather (found in the third column of the table). Notice that the symbols follow a similar pattern as the symbols for present weather. The plotting model provides for plotting the two most significant past weather events; however, past weather is not a mandatory element and there may be no past weather or only one type of past weather. If past weather is not reported, no symbol is plotted. If past weather is reported, the proper symbol is plotted to the lower right of the station circle.

Problem 7.

On your answer sheet, plot the following surface weather observations. Elements represented by a / (solidus, not the number 1), indicate the observer does not know the value of the element or cannot observe the element for some reason. The / is not plotted but an M may be required if the element is a mandatory element. Some of the stations are identified with three or four letters. Some of the stations are identified with five digits. The three and four letters are assigned by aviation organizations; the Federal Aviation Administration for the United States or other national aviation organizations in other countries. The five-digit identifiers are assigned by the World Meteorological Organization.
Refer to the example of the surface station model provided earlier on this page, and the definitions for the symbols (provided above).

Notes: You do not need to plot the station identifier. Plot only the weather information. However, be sure and indicate a station name with each of your plots. Also, when coding wind direction, remember that the actual direction from which the wind blows is actually "ffx10" (ie, for ff=06, wind direction=060 degrees, or northeast).

Station VV N dd ff TTT TdTdTd PPPPP a ppp ww W Cl Cm Ch

Beckley, WV
72412 6 6 25 06 70 67 1010.3 1 014 91 9 0 3

Ile de Batz,
France, 07117 3 8 27 10 17 14 1016.3 8 005 10 4 6 / /

Bellingshausen,
Antarctica, 89050 7 8 05 12 5 -6 969.2 2 038 40 4 6 / 2

Truk, Caroline
Island 91334 8 7 14 03 25 24 1010.0 2 010 -- 8 1 0 1

Tromso, Norway
01025 7 8 26 15 22 6 1016.9 2 015 16 8 8 6 /

Sornblick,
Austria, 11146 1/4 6 02 06 2 1 1008.9 3 009 41 - 6 5 4

Pucheng, China
58731 5 8 00 00 20 19 1015.8 2 011 25 9 5 7 9

Click here to see a composite map composed of a satellite picture, plotted surface observations for selected stations, an analysis of sea level pressure with fronts and information from weather radars which show the location and intensity of precipitation.

At the bottom of the map are intensity levels in Dbz(from 20 to 55) which show the relative intensity of precipitation, 55 DbZ being the heaviest precipitation. The white areas are clouds. The dark, blue, thin lines are isobars (lines of equal pressure). The heavy blue lines are cold fronts and the heavy red lines are warm fronts. Alternating blue and red mean a stationary front and a heavy purple line is an occluded front. A dashed yellow line indicates a trough of low pressure. Centers of high pressure are indicated with a H and centers of low pressure are indicated with an L .

Study the composite map and answer the following questions.

Problem 8.

Is (are) there any fronts or troughs of low pressure located in Texas?
If so, what type of feature(s) is/are indicated?
Record your answer on the answer sheet.
Print a co lor copy of your map and attach it to your answer sheet

Problem 9.

Is there any precipitation indicated from the radar data located in Texas?
If precipitation is occurring, where in Texas is it located? (Indicate using the terms North, Northeast, East, Southeast, South, Southwest, West, Northwest, Central or a combination.
If precipitation is occurring, what is the maximum intensity level indicated (in Dbz)?
Record your answers on the answer sheet.

Problem 10.

What is the surface wind speed and direction being reported by Amarillo, Texas? Give wind speed in knots and wind direction in degrees (approximate).
Record your answer on the answer sheet.

Problem 11.

Does the composite map you opened show any present weather being reported for any station in Texas? If so, record the present weather number, using the Present Weather Table, and record the station(s) reporting the present weather. Click Here for a figure showing weather observing stations in Texas.
Record your answer on the answer sheet.

Plotting Upper-Air Observation Elements.

The image below is an example of an upper air station plot on a constant-pressure map (at 500 millibars or hectopascals).

The maps of upper-air observations or plots are called constant-pressure maps because the air temperature, dew point depression, wind speed and wind direction plotted on a particular map are all measured at the same pressure level above each station. For instance, on a 500 millibar constant-pressure map, the height at which the 500-mb pressure value is found is different for each station. Thus, instead of doing an analysis of pressure on an upper-air map, an analysis of height is done, much as a topographic map.

Common upper-air (constant-pressure) maps include: 850-mb, 700-mb, 500-mb, 300-mb, 250-mb, 200-mb. The following describes the procedure for plotting the observed data.

Air Temperature (TT). Air Temperature is plotted to the upper left of the station circle (to the nearest whole degree Celsius).

Height of the Constant-Pressure Surface above sea level (hhh) is plotted to the upper right of the station circle. The height of the constant-pressure surface is plotted to the nearest whole meters on the 850- and 700-hPa map and to the nearest tens of meters on the 500-hPa map and those maps aove 500 hPa. Only three digits are plotted. On the 850- and 700-hPa map, the thousands digit is dropped. on the 500-hPa map and above the units digit is dropped.

Dew point depression (DD) is the difference between the air temperature and the dew point. The dew point is always less than, or the same as the air temperature. The dew point depression is plotted to the lower left of the station circle (to the nearest whole degree Celsius). If the dew point depression is equal to 5 or less, the station circle is shaded.

12-hour Height Change (h_ch_c) . The 12-hour height change is the difference between the height of the particular pressure surface 12-hours ago and the current height. It is plotted (in decameters) to the lower right of the station circle.

The sample plot of upper air data, provided earlier, provides station data for the 500hPa level. The plot shows the winds are from about 250 ^o at 65 knots, the temperature is -15^oC, the dew point depression is 7 degrees, making the dew point -22 ^oC. The height of the 500 mb surface above sea level is 5400 meters, and has fallen 20 meters during the previous 12 hours.

Click here for the latest analysis for upper-air conditions at a level of 500 hPa. The standard method is for the units digit of the height of 500 hPa to be rounded up or down to the nearest tens of meters when plotted on the map. Thus, a height of 5854 meters is normally plotted as 585 (interpreted as 5850 meters). Note: The heights are easily converted by simply placing a "0" at the end of the code. Data is plotted about the station circles in green. The gray lines are contours, or isoheights. The, dashed lines are isotherms.

Problem 12.
What is the temperature recorded at a pressure of 500hPa above Brownsville? What is the dew point? Be certain to include the proper units with your answers. Record your answers on your answer sheet.
Print a copy of your map and attach it to your answer sheet

Click here for the latest 850 hPa map analysis. Like the 500 hPa map, the gray lines represent isoheights (contours), lines of equal height; the dashed, lines represent isotherms, lines of equal temperature. Wind speed, wind direction, air temperature, dew point and height are all plotted in green about the station circle. Heights are converted by simply adding a "1" at the beginning of each code. For instance, a code of 518 represents a height above sea level of 1518 meters.

Problem 13.
What is the wind speed at the pressure level of 850 hPa at Fort Worth? Be certain you use the proper units for the wind speed.
Record your answer on the answer sheet.
Print a copy of your map and attach it to your answer sheet

The table of problem 14 provides data obtained from rawinsonde observations. A rawinsonde or radiosonde is an instrument package carried upward by a balloon to sense and transmit the value of air temperature, amount of water vapor in the air, air pressure and -for a rawinsonde- wind speed and direction can be obtained. The basic difference between a radiosonde and a rawinsonde observation is that a rawinsonde observation also has wind data which is may be obtained by ground equipment tracking the "sonde" and obtaining elevation and azimuth angles from which the wind speed and direction can be determined, or by navigation aids, the latest being Global Positioning Satellites, from which the location of the "sonde" can be determined.

"Ground equipment" used to track "sondes" and also to collect the temperature, humidity, and pressure information transmitted from the "sonde." The system is called a rawinsonde system.

If tracking is not possible, only information which is transmitted by radio back to the ground equipment is available. This is typically temperature, humidity and reference signals from which pressure values can be obtained. Only a simple antenna is required to receive the information. This system is a radiosonde system. Global positioning sondes have an additional antenna to receive signals from global positioning satellites.

The table below gives the station name, the five-digit identifier for the station, (called the block and station number), the temperature, the dew point, the height at which the measurement was made and the wind direction and wind speed at this height. We are using data only for the level at which a pressure of 500 hPa is found. As you can see, a pressure of 500 hPa is found at different heights in the atmosphere. A pressure of 500 hPa is approximately 7.25 pounds per square inch.

Problem 14.

On your answer sheet, plot the following upper air data in the proper location and manner about the station circles on the answer sheet using the upper-air plot model and definitions of symbols provided.

Station
Id. Air
Temp.
(C) Dew Point
Temp.
(C) Height
(meters) Wind
Direction
(degrees) Wind
Speed
(knots)

Resolute N.W.T.
71924 -17 -25 5650 310 36

Miami,
Fl. 72202 -5 -21 5890 020 08

Topeka,
Ks. 72456 -7 -11 5880 195 13

Akraberg,
Denmark
06009 -21 -34 5590 115 14

Quillayute,
Wa. 72797 -9 -23 5810 295 21

Sundoval,
Sweden
02365 -19 -31 5660 300 35