Saturday, May 1, 2010

Indigenous Weather Knowledge

One of the oldest ways of forecasting the weather comes from the indigenous peoples around the world, including the Australian Aborigines. These techniques evolved over many thousands of years and involved observing linkages between the weather and the behaviour of various plant and animal species.

Initially dismissed by western science, it has only recently been realised that there is an underlying scientific basis underpinning much of the indigenous weather knowledge (IWK), and a renewed interest has resulted.

There are many examples of IWK, both from Australia and around the world, and only a few are given here – the first three from Australia and the other two from external sources.

(a) The gidgee tree: This is a type of acacia native to inland Australia, and the belief is that when you can smell the gidgee tree, rain is on the way. It turns out that when the air humidity rises, the tree exudes a pungent smelling sap. And rising humidity is often associated with the onset of rain. This knowledge comes to us through peoples from various inland areas of NSW and Queensland.

(b) Flying foxes: In the Northern Territory, these large fruit bats move from inland areas to the riverbanks when the dry season is imminent and back the other way when the wet season is about to start. This behaviour is used by the local people to predict the changes of season.

A flying fox colony in northern Australia. (Image: Justin Welbergen, Wikipedia commons - click to enlarge)

(c) Brolga: The brolga is a large bird in the crane family. Its breeding is determined largely by rainfall and in the tropics takes place soon after the end of the wet season, from February to May. When breeding behaviour is observed early in the year it is taken as a sign that the dry season is imminent.


The mating behaviour of the brolga is used to forecast the onset of the dry season in tropical Australia.
(Image: Wikipedia commons - click to enlarge)

(d) Mango tree: A belief common to several Pacific Island peoples concerns the flowering of the mango tree – if this happens earlier then normal it is said to imply an increased number of tropical cyclones in the upcoming season. The modern explanation is that the mango tree will flower early if temperatures are warmer than normal and this occurs across island areas when the surrounding sea surface temperatures are warmer than normal. And warmer ocean temperatures promote increased tropical cyclone formation.
These conditions are characterised by what we today call the "La Nina".

The mango tree in flower - the timing of the blossoms is related to the intensity of the upcoming tropical cyclone season.
(Image: Wikipedia commons - click to enlarge)

(d) South American Sea Temperatures: For thousands of years, native Peruvian fisherman trolled for anchovies, a cold water fish that thrives off the coast of South America. However they observed that during some years warm water develops along the coastline, killing the anchovies by the hundreds of thousands. The local peoples monitored the ocean temperatures by immersion and “feel”, and when these warmer waters were detected, they planted increased crops of sweet potatoes in anticipation of reduced anchovy catches. Today we know this warm water development off the coast of South America as "El Nino".

Indigenous weather knowledge is a fascinating topic and because of its great antiquity forms a valuable goldmine of information that can be well integrated into today's scientific knowledge.

The Bureau of Meteorology web site contains some fascinating information on this subject at:

http://www.bom.gov.au/iwk/

For some other information on the more usual ways of defining the seasons go to

http://passingparade-2009.blogspot.com.au/2012/05/defining-seasons.html


Reference: The Complete Book of Australian Weather, Richard Whitaker
Allen and Unwin, 2010

2 comments:

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