Convection Charts

The convection charts are invaluable for any traveler in Luftreich. Almost all mid-distance travel vehicles (covering distances from tens to hundreds of kilometers) are propelled by the prevailing wind currents, making it essential to understand these patterns in order to optimize transportAation and to avoid being swept away into unknown territory with no plan for how to return.
The overall quality of these documents varies widely from one village to the next, depending on their societal needs. In the more insular tribes, most of these maps are merely vague mental notes gathered from conversations and general hearsay, hardly trustworthy for even an amateur navigator. However, in certain communities who serve as trade intermediaries for their regional neighbors, they have become more systematic in their charted observations, which they record on large rolls of canvas for safekeeping and portability. Since few scientists cartographers have explored even a minute fraction of the world’s airspace, and fewer still know all the seasonal variations in these winds, almost all these charts are local in scope and far from perfect.
Even the Central Empire’s own official wind charts do not extend far beyond the zone of the Empire’s control, and the imperial post officers often complain that the maps given to them are rife with errors. And yet it is said that some of the most resourceful unincorporated merchant villages, beyond the southernmost limits of the Empire, may have pieced together records of much larger scale and quality through their years of trading. If this is true, they are doubtless very cautious about sharing their geographical and meteorological expertise, instead guarding this information as a precious trade secret.

Purpose

Navigation / transportation

Document Structure

Clauses

A convection chart of average quality will first contain a map giving a 2D view of the region of interest, overlayed with numbered arrows showing the main currents. Depending on the level of detail and the knowledge of seasonality, there may be secondary or tertiary arrows displaying other observed wind patterns.
Any decent chart will display additional 2D slices of the 3D space of the region, showing how the currents move through the space not only from a birds-eye view, but also the altitude profiles of these currents.
Accompanying the maps are many tables containing the speed, temperature, seasonality of each of these currents. Some charts also have attached expert wisdom about the main currents themselves and any inherent dangers associated with traveling by them. These might range from from stream-of-consciousness notes taken from a traveler's log, to highly detailed scientific reports.
The highest-quality charts contain hundreds or even thousands of 2D stacked and sliced maps accompanied by an even greater number of numerical tables, to ensure a perfect understanding of the regional wind dynamics. (To complete such a detailed chart, even for a fairly small territory, takes years for a dedicated team and may consume a lifetime for a solo cartographer.)

Caveats

Most charts easily obtainable to the general public are of dubious quality, and using such a document for navigation on any lengthy journey is simply inviting disaster.

Type

Report, Scientific

Medium

Canvas