Friday, 10 June 2011
Cumulatrive Detritus of a Life of Math Teaching
Cumulative / Accumulate The words accumulate and cumulative both refer to the grouping together of other objects or sets and both come from the ancient Indo-European root kou from which we also get words like cave, cage, cavity and excavate. By the time the Romans adopted cumulare for a heap or collection of objects, the meaning had apparently extended to the pile made in creating a cave or cavity. Today cumulative often refers to successive additions, as in the statistical use when we talk about the normal Cumulative distribution function. Accumulate, on the other hand, often suggests collecting all at once.
As I look out at the Norfok shire sky, there are huge cumulus clouds. That's probably a good thing, I just read this moring that this part of East Anglia is officially in a drought. And all my friends in the US think it is always rainy in England.
A cumulus cloud is so called because it looks like a heaped mass, a pile of cloud. Which prompts me to provide a note on cloud names from The Weather Doctor Cirrus, stratus, cumulus. We take these terms to describe the clouds above us pretty much for granted these days, often assuming they are names of ancient origin. While great age can be ascribed to their Latin roots, the specific terms for various basic cloud forms are not yet two centuries old and were only accepted as the international standards during the Twentieth Century. The man whom we must credit with developing the basis for our cloud classification system was Luke Howard (1772-1864), an English manufacturing chemist and pharmacist. Like many who observed and studied the workings of the atmosphere at that time, Howard was an amateur meteorologist. Despite that fact he produced several landmark works including On the Modification of Clouds, The Climate of London, and Seven Lectures on Meteorology, the first textbook on weather.