Fire rituals are an integral part of ancient traditions across the world. Agnihotra is one such very significant ancient Vedic fire ritual which is widely practiced even today. Its purifying impact on the environment, atmosphere, and water systems are now being scientifically researched and established. In this article, we explore the link of this fire ritual with rainfall.
What is Agnihotra?
Agnihotra is a simple Yajna performed during sunrise and sunset by burning dried cow dung in a fire pit made of copper in the shape of an inverted pyramid. Sticks known as Samidhas are obtained from medicinal trees with specific properties and are burnt while adding cow ghee, rice, dried herbs and other fragrant herbs as oblations. Agnihotra is a bio-energy fumigation process carried out by specialists.
Relation between fire and rain:
The following verse from the Bhagavad Gita relates the performance of Yajnas with rain:
annād bhavanti bhūtāni parjanyād anna-sambhavaḥ
yajñād bhavati parjanyo yajñaḥ karma-samudbhavaḥ (BG 3.14)
All living beings subsist on food, and food is produced by rains. Rains come from the performance of sacrifice, and sacrifice is produced by the performance of prescribed duties.
To understand how agnihotra aids in rain, let us look at what causes cloud formation and rain. If we look at it fundamentally, it is heat that produces rain. The heat from the sun causes water from different sources to evaporate, rise high into the sky and form clouds. This deep understanding is reflected in the following verse from Linga Purana: “After being heated by the Sun, water contained in most of the materials on earth gets converted to smoke (vapour) and ascends to sky with the air and subsequently gets converted to cloud. Thus the combination of smoke, fire and air is the cause of cloud formation. These clouds cause rainfall under the guidance of Lord Indra, having thousand eyes”. A severe form of this can be seen during volcanic eruptions and forest fires, when the huge flames create their own clouds known as pyrocumulus, which means “fire cloud” which produces localized rain.
The water vapour requires a non-gaseous surface to condense and form clouds. In the atmosphere, this surface presents itself as tiny solid or liquid particles called Cloud Condensation Nuclei (CCN). These CCNs, their number and size are important to form the cloud and precipitation. When these water droplets get too heavy to stay suspended in the cloud, they fall to Earth as rain. Agnihotra causes the fumigated particles to get released into the atmosphere at high velocities and rise high enough to cause coagulation to form clouds and subsequent condensation to give rains.
Agnihotra and rain:
The temperature in the Agnihotra fire pit is typically between 200 to 1000 degrees Celsius or above. At this temperature generally all added materials are vaporized and the molecules, ions or nanoparticles rise high into the atmosphere. Ghee, prepared from cow milk, consists of minerals like Fe, and Cu etc., and on fumigation these molecules, with high kinetic energy, travel long distances and climb great heights as the density of these vapors are lesser than the surrounding air. It is found that these vapours are capable of purifying the atmosphere, aid in cloud formation and cause good rainfall by acting as CCNs to form liquid droplets. Hence Yajnas significantly impact the water cycle and produce rain.
A study  was conducted in Atlanta, where a Yajna experiment was conducted on a large scale at different times of the year for 8 years and the rainfall pattern was studied over 23 years. It was found that the rainfall quantity increased during the years when Yajna was performed compared to the years when there was no Yajna.
The addition of cow products plays an important role with the chemical composition of cow’s and buffalo’s milk containing metals like iron (Fe), copper (Cu), manganese (Mn), and Zinc (Zn), which on fumigation are released into the atmosphere to a good extent. With high velocities caused due to high temperature in the fire pit, when they collide with atmospheric molecules (particulate matter or any pollutant) can excite them and cause dissociation, thereby also purifying air.
Yajnas are responsible indirectly for regulating the micro climate and continuation of seasonal cycles by impacting the humidity, heaviness and other properties of the atmosphere. They can significantly impact cloud formation as well as precipitation leading to rainfall and also the quality of rainfall.
 Yajna causes good rainfall — http://ijiset.com/vol7/v7s2/IJISET_V7_I2_05.pdf
 Agnihotra technology in the perspectives of modern science – A review:
 Hydrology in Ancient India — http://184.108.40.206/rbis/vedic.htm
 The Mystical Wonder of Rains — https://www.hinduscriptures.com/vedic-culture/nature-worship/mystical-wonder-rains/7596/
 Yajna can increase humidity even in winter — http://www.ijsrp.org/research-paper-0121/ijsrp-p10939.pdf
 Hydrological knowledge in ancient India (all verses) — http://220.127.116.11:8080/jspui/bitstream/123456789/184/1/Hydrological%20Knowledge%20in%20Ancient%20India.pdf