Possible Clues:

• The line from the meteorologist's office is - half the creative work is left to the layout
• Institute gets most of the letters back to lease hot line from the meteorologist's office
• Pit holes spoilt with wavy streaks important to The Met
• Map line of equal value of a climatic variable
• He spoilt model with wavy streaks important to the Met
• Line on a map connecting points having equal meteorological incidence
• Graph showing climatic variations
• Man, perhaps putting work in, shortened the line on map