You must have come across the irritating sound resulting from a sharp object scratching another rough surface. Ever wondered what it is called? Finger nails scraping a blackboard It is called 'Grima' Although it is not yet included in standard English, mostly Spanish speakers call it so, when they hear this unpleasant sound, resulting from a chalk or nails scratching against a blackboard, a fork scratching a plate, nails scratching a wall etc. Psychologists say, it should be considered distinct from other emotions. It is seen that some people can bear this sound to some extent whereas some can't bear it even for a second. What Spanish speakers mean by 'Grima' is, an unpleasant sensation, shivering and repulsion. Stimuli that draws it out , includes squeaking noises of doors, scratching with fingernails on surfaces etc. It is rated as less pleasant than disgust. It is also seen that people get a sensation of itchy skin and goosebumps in such cases. Research: Over ...
Ever encountered a strange musty, sweet smell when it rains after a prolonged warm, dry weather?
This article is about the pleasant earthy scent, called 'Petrichor', produced when rain hits dry soil. It is derived from the Greek word 'Petra' which means 'Rock', and 'Ichor' which means the fluid, as blood of God.
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| The strange, sweet fragrance of Petrichor after rain. |
Origine:
This phenomenon was scientifically described for the first time in the year 1964 by Austrailian researchers, Isabel Bear and Dick thomas. Thomas coined the term 'Petrichor' to refer to, what earlier was known as 'argillaceous odour'.
The authors also described in an article how the fragrance derives from an oil released by some plants during droughts, where it is soaked by rocks and soils.
When it rains, the oil is let out to the air along with 'geosmin', a metabolic by-product of some actinobacteria, which is released by wet soil, producing this distinct scent.
Mechanism:
In 2015, scientists at MIT, used advanced cameras to record how the fragrance travels into the air. The test involved around 600 experiments on 28 various surfaces.
Observations:
When a raindrop hits an absorbent surface, air from the pores creates tiny bubbles, which move to the surface and emit aerosols. These aerosols convey the smell as well as viruses and bacteria from the soil.
It is also observed that raindrops that move at a slower rate, tend to produce more aerosols which is why, the Petrichor is more common after light rains or drizzling.
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| Observations on the forming of Petrichor |
Psychological effect:
The human smelling capacity is hugely responsive to Geosmin and, has the capability to sense the least possible concentrations. Some scientists believe that humans appreciate the rain fragrance or 'Petrichor' because their predecessors may have been dependent on rainy weather for survival.
So, the next time a musty, sweet fragrance hits your nose during rain, you know what to call it!
Thank you so much for going through this article.
Its very informative ☺
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