Ever wondered why this year's rainy season is extended and furious?
The answer may lie in the Vedas and Hindu Shastra. Various ancient Sanskrit texts describe cyclic variations in Indian monsoon rainfall occurring every 3, 5, 7, 18, and 60 years. Time series analysis of seasonal rainfall data shows significant peaks near these periods.
We should all know that Venus, Mars, and Jupiter are nearest to the Earth in nearly 1.6, 15-17, and 59-63 years respectively. Indian rainfall oscillates every 2–3, 5–7, 11–12, 18–20, and 60 years. Narasimha and Kailas, using wavelet analysis, confirmed the first four patterns. These cycles vary in amplitude and phase, based on 100 years of data.
Let's check what we have got.
The monsoon season, known for bringing rain to much of the country, has been depicted in literature since the Rigveda. Vedic texts describe the evaporation-rainfall cycle effected by the Sun.
Out of 3,5,7,18,60 years cycle, 3 and 60 sems to have strong correlation with the rainy season. We shall discuss 3 and 60 with proofs while 5,7,18 we will see what our ancient astronomers have got
2 Years cycle : Venus
Venus appearance cycle (2-3 years cycle)
Orbitting Venus is nearest to the earth in 1.6 years, two venus orbit however makes roughtly 3 monsoon cycles.
Kautilya’s Arthaśāstra written in 4th century bce observed this phenomenon and its link to the variability in yearly rainfalls based on rainfall figures collected by the metrological department of that time.
In Chapter Agriculture (II.24) he mentions that rainfall for the
season depends on the visibility of Venus
"tasyopalabdhih sukrodayāstamayacārebhyah śukrādvrriti"
Kautilya expects good rainfall if Venus were to be sighted in the eastern sky during the monsoon season.
As per data analytics, the Venus visibility portent stated in the Arthaśāstra appears to be a proxy for the near three-year fluctuation cycle in the rainfall called the EMSO signature.
60 Year cycles (corresponding to Jupiter being the nearest)
in Dec 2024 the Jupiter will be nearest to the earth in 59 years. Last it was nearest in 1963
1904- The 12 years average TYA rainfall started to rise after Jupiter was nearest
1962 - The TYA started to decline after Jupiter was nearest to the earth
2024- The TYA with higher low and a good monsoon indicates good monsoon seasons 12 years hence. Let us see what it turns out to be.
However, it seems there is a good correlation between Jupiter being nearer to earth and the rainfall
5 Years Cycle
During the Vedic period, a luni-solar calendar was used. Details of its original form and evolution are unclear, but from the Vedānga Jyotisa, we know it was a five-year cycle called the Yuga.
Varāha-mihira, in his Brhatsamhitā, presents the older five-year division for rainfall prognosis. This appears in Chapter 8, verses 24 and 25.
Samvatsaro’gnih parivatsaro’rka
idādikah śītamayūkhamālī
Prajāpatiścapyanuvatsarah
syādidvatsarah śailasutāpatiśca
Vrstih samādye pramukhe
dvitīye prbhūtatoyā kathita trtīye
Paścājjalam muncati yaccaturtham
svalpodakam pancamamabdamuktam
7-year cycle
It appears to belong to the early centuries of the Common Era, as it uses the Śaka Era (78 CE) in its algorithm for predicting rainfall. It postulates a seven-year cycle, based on the presumed influence of the seven planets on rainfall. Historically, this parallels the development of the names of the seven days of the week, attributed to the sun, moon, and five planets, which most likely occurred at the beginning of the Common Era.
18 years cycle (roughly corresponds to Mars being nearest to Earth).
I tried to plot 18 years cycle of Mars on a 110 years data set but there seems to be no correlation or it needs more scientific insights.
More details at below link
researchgate.net/publication/237247119_Monsoon_rainfall_cycles_as_depicted_in_ancient_Sanskrit_texts
imdpune.gov.in/library/public/e-book110.pdf#:~:text=This%20CD%2DROM%20contains%20actual%20monthly%2C%20annual%20and,Homogeneous.%20Regions%2C%20Met%20Sub%2Ddivisions%2C%20States%20and%20Districts.