Final answer:
Flow line maps are mainly used for analyzing transportation networks and studying weather patterns, aiding in the visualization of spatial data and numerical information.
Step-by-step explanation:
Flow line maps are used for various purposes in geography and related fields. They are most often used for analyzing transportation networks and studying weather patterns. These maps can illustrate the movement of different modes of transport, showing the density and direction of routes, which is critical for evaluating the significance of major technological innovations in transportation that modify the physical environment. In meteorology, flow line maps, using vectors to represent forces, can indicate the strength and direction of winds, which helps in predicting weather patterns.
Additionally, flow line maps can help to condense detailed numerical information into a visual form, making it easier to identify relationships and patterns. In this way, they're an essential tool for geographers and economists alike to analyze and interpret spatial data and build an intuitive grasp of complex information.