Name ____________________________________________ 39. To actually find the longitude, what must you find first? Second? 40. What is the rate of motion across the sky for the sun? 41. What is your location if local time is earlier than Greenwich time? 42. What is your location if local time is later than Greenwich time? 43. Define what is meant by a field. 44. Define isoline. Period ______ Code # ______ 45. Define isotherm. 46. Define isobar. 47. Define contour line. 48. What is the purpose of a topographic map? 49. What is the purpose of contour lines drawn on a contour map? 50. Define contour interval. 51. How is a steep slope indicated on a contour map?