Harvard researchers have found that raindrops are remarkably similar in different planetary environments, even planets that are radically different like Earth and Jupiter.
It might interest you: They reveal a great diversity of deep-sea species
Understanding the behavior of raindrops on other planets is fundamental not only in detecting ancient weather on planets such as Mars, but also in identifying habitable planets outside our solar system.
“The life cycle of clouds is really important when we think about the habitability of a planet,” said Caitlin Loftus, a graduate student in the Department of Earth and Planetary Sciences and lead author of the paper, in a statement.
“But clouds and precipitation are really complex and too complex to fully model them. We’re looking for simpler ways to understand how clouds develop, and the first step is whether cloud droplets evaporate into the atmosphere or reach the surface. In the form of rain.”
See also: These are the eight new Geoparks designated by UNESCO
Said Robin Wordsworth, Associate Professor of Environmental Science and Engineering at Harvard’s John A. Paulson School of Engineering and Applied Sciences (SEAS) and author. Main article: “The humble raindrop is a vital component of the precipitation cycle for all planets.
“If we understand how individual raindrops behave, we can better represent rain in complex climate models,” he added.
A key aspect of raindrops behavior is, at least for climate designers, whether or not the droplet reaches the planet’s surface because water in the atmosphere plays an important role in a planet’s climate. To this end, size matters.
In Other Science News: Twenty Years Since the Journey of the Space Tourism Pioneer
Too large and the drop will disintegrate due to insufficient surface tension, regardless of whether the water, methane, or liquid iron is very hot as is the case on an exoplanet called WASP-76b. Too small and the droplet will evaporate before hitting the surface.
Wordsworth Loftus defined an ideal area for raindrop size using only three characteristics: droplet shape, rate of fall, and rate of evaporation.
The droplet shapes are similar in different rain materials and mainly depend on the weight of the droplet. While many of us can imagine a traditional teardrop-shaped drop, raindrops are actually spherical when young and multiply as they grow until they take on a shape like the top of a hamburger bun. The rate of fall depends on this shape as well as on the attractiveness and thickness of the surrounding air.
The rate of evaporation is more complex, as it is influenced by the composition of the atmosphere, pressure, temperature, relative humidity, etc.
By taking all these properties into account, Loftus and Wordsworth found that under a wide range of planetary conditions, the mathematics of raindrops means that a very small fraction of the potential droplet sizes in the cloud could reach the surface.
Also: What do I do if my dog eats chocolate?
“We can use this behavior to guide us while modeling cloud cycles on exoplanets,” said Loftus.
“The insights we get from thinking about raindrops and clouds in different environments are key to understanding the habitability of exoplanets,” Wordsworth said. “In the long term, they can also help us gain a deeper understanding of Earth’s climate.”