Part I Maps and Numbers

 Station Models  Isoline Maps

Station model: an abbreviated plot of weather station data

Station model: abbreviation of weather station data

Station model: Text, pp , textbook Cloud cover Wind direction Wind speed Pressure (without decimal point; without initial 10 or 9)(mb) Air Temperature Dew point Present weather pressure change in past 3 hrs (without decimal pt)

Cloud cover  Circle centered on station location scattered overcast

Air temp; dew point temp Air temp Dew pt temp

Wind direction Direction arrow points is wind direction (direction wind is coming FROM) If calm, no arrow and double circle

Wind speed

“knot” Nautical mile per hour 1 knot = 1.15 mph; 1.9 km/hr

Present weather

Current pressure numbers; in mb; no decimal point; 10 or 9 at beginning of number is NOT shown 162 = mb Does number begin with “10” or “9” ?

 353 ?  mb  175?  mb  985?  mb  893?  mb  074?  mb  890?  989 mb

Pressure tendency during past three hours 02 Amount of change; mb; No decimal shown;

07 13

Last night

Station Model Exercise :  In pairs:  Pick any 4 cities and make station models.  Each pair make 4

Isoline maps Interpolate between discrete data points to create a continuous “surface”:  Helps us to visualize the data examples:  Elevation surface  Pressure surface  Temperature surface

Topographic map an elevation surface Contour lines

Temperature map isotherms

Pressure surface isobars

Isolines “connect points of equal value” Types of isolines:  Isobars: pressure  Isotherms: temperature  Isohyets: precipitation amount  Isodrosotherms: dew point  Isogons: wind direction  Isotachs: wind speed  Isoshears : wind shear

 All data values on an isoline are equal.  The interval between lines is constant for the entire map

Rules for making an isoline map: Lower values are always on one side of isoline ; higher values on the other side. Isolines NEVER CROSS OR TOUCH, NEVER SPLIT. Isolines will generally be SMOOTH AND PARALLEL. LABEL each isoline on the ends for open and in the center for closed isolines. Interpolate between points as exactly as possible! Do NOT draw lines where there are no data points. Use a pencil 35

 Trough: line of relatively low values  (Isolines point to higher values)  Ridge: line of relatively high values  (Isolines point toward lower values) Terms usually used on pressure maps

 Gradient  Steep/strong gradient: close isolines  Weak gradient: widely spaced isolines

miles

Exercise Create an isobar map from Station Models (station model map of US Plains states)  Use a 5 mb interval, starting at Identify the pressure on each station model. Remember to:  A) insert the decimal to give the number a tenths place  B) add a 9 if the first number is greater than 5 or a 10 if the first number is less than 5. examples: 184 = mb; 997 = mb