Isolines and Topographic Maps
DO NOW What is an isoline? An isoline is a line connecting points of equal value. What are isolines that connect equal points of temperature called? Isotherms What are isolines that connect points of equal pressure called? Isobars
Topographic Maps Contour Line – - line on a map that connects points of EQUAL elevation. - show elevation and shape of the land
Topographic Maps Two dimensional model of the Earth’s surface (represents 3-D world) Topographic maps are also known as contour maps. Show elevation above sea level using contour lines.
Topographic Maps Contour Interval – difference in elevation between each line. MUST be equal spacing. Contour interval = 20 feet 580 560 540 520
“Real World” Contour Map
Rules for Contours 1. Contours bend upstream (uphill) when crossing a stream.
399 179 239
Rules for Contours 2. The maximum possible elevation for a hill is “1” less than what the next contour “should” be. The highest possible elevation of the hill is just below the value of the next line that is not shown 90 80 70 60 50
Closely Spaced Contours Steeper Slope (Gradient) – contour lines are closer together.
Wide Spaced Contours Gradual/Gentle Slope (Gradient) – contour lines are farther apart.
A B
Depressions Contour lines which show a depression, crater, or sinkhole on a map. Shown by dashed lines on the inside of a contour line
100 100 50
Rules for Contours The lowest possible elevation for a depression is “1” more than what the next contour “should” be. The lowest possible elevation of a depression is just above the value of the next line that is not shown 90 90 51 80 70 60 50
Let’s make a map!! Contour map 1
Highlight data points.
Fill in gaps in data.
Connect the dots.
Go on to the next value.
Another map!! Contour map 2
Isotherms Lines on a map that connect points of equal temperature
What is an Air Mass? Air masses are large bodies of air which have similar temperature and moisture characteristics. Air masses form when air stays over a region (called the source region) for several days. Air masses that form over water will be moist. Air masses that form over land will be dry.
A = Arctic P = Polar T = tropic c - continental = dry m - maritime= moist A = Arctic P = Polar T = tropic
Isobars Lines on a map that connect points of equal pressure
Pressure- Measured with a barometer Pressure is the weight of air pushing down. Describes the air systems that cause weather. HIGH PRESSURES: Cooler Less Moisture Clear Skies H Good Weather LOW PRESSURES: Warmer More Moisture Precipitation Likely Bad Weather L