FIELD MAPPING AND ISOLINES Ms Susinno A field

FIELD MAPPING AND ISOLINES Ms. Susinno

• A field map shows a region with a measurable quantity at every location.

ISOLINES • An isoline is a line connecting points of equal value.

EXAMPLES OF ISOLINES: • Isotherms: • points of equal temperature • Isobar: • points of equal barometric (air) pressure • Contour: • points of equal elevation • Anything else you can get a value for. Examples-points of equal: depth, chemical concentration, decibels, damage scale values, ice thickness, snowfall/rainfall totals…

EXAMPLES OF ISOBARS:

EXAMPLES OF ISOTHERMS

EXAMPLES OF CONTOUR LINES on topographic maps

EXAMPLES OF ISOBATHS

EXAMPLES OF ISOPACH MAP MEASURING GLACIER THICKNESS

RULES FOR DRAWING ISOLINES: Isolines connect points of equal value. The line must go through the center of the dot. You MUST use pencil! 5 5 10 10 15 15

Isolines are gentle, curving lines- No sharp corners! No double or messy lines! 5 5 10 10 10 15 15

Isolines are always closed curves even though the map might only show part of it. Your line must be a closed loop or reach the edge of the map!

Isolines NEVER cross- this would mean that one point has two different values. Ex: one spot has two temperatures? Oh no! 40 ° 50 ° 30 ° 60 ° X 20° Y Z

Isolines usually are parallel ish. (They have a parallel trend. )

LABELING! Isolines are always labeled! 60 50 40 70 Inside the line for contour lines or closed loops

Isolines are always labeled! LABELING! Or at the end of the line where they reach the edge of the field or map Either way is acceptable

Isolines are always labeled! Isolines are NEVER labeled between the lines! 50 ° Which line is 50 ° ?

GRADIENT • Gradient shows how quickly the value changes from one point to another. Another world for gradient is SLOPE

• A steep (high) gradient changes quickly and the isolines are close together. • A gentle (low) gradient changes slowly and the lines are far apart. Gentle area Steep area

AUG. ‘ 05

THE END!