Does the Smell of Rain Heighten Our Senses?
The source of the smell is a combination of oils and chemicals. Apparently, during a dry spell plants secrete the oils to signal the halt of root growth and seed germination, while the chemicals come from the reactions of bacteria.
Rain falling on dusty soils is infused with this mixture and the smell is released when tiny air bubbles rise and burst out of a raindrop, throwing out a very fine spray.
How did the scientists make this discovery?
Using high-speed cameras, Massachusetts Institute of Technology researchers were able to film air bubbles rising through raindrops like they do in sparkling wine.
Smell is just one of our senses
We have become more aware of the importance of our senses during the Covid 19 pandemic with one of the symptoms being the loss of taste and smell.
Our tongues have thousands of taste buds that help us to sense 5 types of taste - sweet, salty, bitter, sour and umami. A combination of taste and smell leads to flavor which can mean your food tastes differently if your nose is blocked. You might not know that spicy is not a taste. It is actually a pain signal according to the National Library of Medicine
The five tastes can be sensed on all parts of the tongue, although the sides are more sensitive than the middle. About half of the sensory cells in taste buds react to several of the five basic tastes. The cells differ in their level being produced once all the information from the different parts of the tongue is combined. Texture can also contribute to taste.
Our noses have a large number of receptors placed in the upper reaches which sense smell using mucus-covered cilia - like tiny hairs - that will respond to any molecules that come with a smell. The olfactory cortex that receives and processes these signals is in the front of the brain.
While we do not have as many smelling receptors as those animals that are super smellers (dogs for example), the more complicated human brain makes up for the smaller number. Unfortunately, our ability to smell can lessen with age and in some, may even be a symptom of a medical condition.
In the case of sight, the receptors are in the back of the eye on the retina. Rods are used for black and white vision while cones are for color vision. Vision is processed in the occipital cortex. The right side of the visual cortex processes signals from the left visual field and the right visual field is processed in the left visual cortex. Those rods also give humans vision when there is limited light available - at night for example. The information translated from the light is sent as electrical impulses to the brain through the optic nerve.
Hearing involves a complex chain of processes, ending up in the inner ear in a spiral-shape cavity. This is called the cochlea and it is where the mechanical signal is turned into an electrical signal to send it to the auditory cortex in the center of the brain.
We retain our sense of balance because the Eustachian tube in the middle ear equalizes the air pressure there with the air pressure in the atmosphere. The vestibular complex (in the inner ear) is also important for balance because it contains receptors that regulate a sense of equilibrium.
The skin is the body's largest organ with millions of touch receptors responding to touch, to pressure, to pain and to temperature. The somatosensory cortex processes these signals. There are additional receptors in our fingertips, our lips and our eyelids making them extra sensitive to touch.
Touch is believed to be the first sense that we develop. Touch is more than just a sense, it helps convey compassion from one human to another while it can even influence how we make decisions. Studies by psychologists at Harvard and Yale found that texture can be associated with abstract concepts, and touching something with a texture can influence the decisions a person makes.