Until now, popular belief has defined raindrops as teardrop-shaped. This conception has been perpetuated in drawings and media representations, but, as the NASA, this idea is far from correct.
NASA researcher, Chris kidd, explained that raindrops are not at all like tears, but their shape is more like that of a hamburger 'bread due to the pressure variations they experience as they fall. This characterization is crucial to understanding not only the shape of the droplets, but also how they influence our climate.
The phases of raindrops
Chris Kidd has identified that water droplets go through three distinct phases during their formation and fall:
- Initial phase: Droplets begin life as small water balloons, in which water molecules stick together. This structure allows them to maintain their rounded shape due to the surface tension of the water.
- Drop and distortion: As the drops descend, the air pressure They encounter pressure from below as they fall, distorting their shape. This pressure causes the top of the drop to maintain a spherical shape, while the bottom flattens, resembling a hamburger bun.
- Before breaking: Just before a drop breaks, it transforms into a shape that Kidd has compared to a parachuteThis change in shape occurs due to the accumulation of weight and air resistance.
Why is it important to know the shape of raindrops?
Although it may seem like a trivial discovery, understanding the actual shape of raindrops has significant implications. Kidd highlights that this information can be used to improve advice to emergency services in flood situations, as well as optimize the aviation, especially during storms. In this way, weather patterns and raindrop dynamics can contribute to better management of adverse weather events. In addition, to understand how the artificial rain affects the weather, it is crucial to know the shape of the drops.
Sizes and Shapes of Raindrops
Raindrops come in a variety of sizes, and their shape can vary considerably depending on their diameter. In the case of drops that fall as drizzle, these are small, with a diameter of about 0.1 mm. This small dimension generates a large surface area compared to its mass, allowing them to be spherical and fall slowly due to the surface tension.
As the droplet size increases until reaching 2 mm in diameter, the surface becomes 400 times larger than the drizzle, and its mass is 8,000 times greater. This means that mass plays a greater role in shaping its shape, which will no longer be spherical. In this case, the air force creates a flatter shape at the bottom while the top remains more rounded.
Finally, the raindrops that reach 5 mm in diameter have a surface area 2,500 times larger than drizzle, but their mass is 125,000 times higherThis results in droplets falling rapidly and flattening further, eventually conforming to a shape that may resemble a parachute, before surface tension fails and the droplet breaks into multiple smaller droplets, a phenomenon that is crucial for the water cycle in our atmosphere.
Mechanisms of Raindrop Formation
The water cycle is a complex process involving several mechanisms of raindrop formation. It is often taught that the cycle begins with the evaporation from sea and ocean water, which then condenses into clouds. However, scientists have managed to identify more details about how these droplets actually form.
- Condensation: Raindrops form when water vapor cools and condenses on condensation nuclei, microscopic particles present in the atmosphere. These nuclei may include dust, pollen, and sea salts.
- Collision and coalescence: Once droplets begin to form, other small droplets may collide with them. This collision process allows larger droplets to gain size at the expense of smaller ones, an essential aspect of rain formation.
- Bergeron-Findeisen Theory: This is another mechanism that is activated in situations where there are ice crystals in the clouds. As these ice droplets turn into water, they can trap other water droplets, increasing their size before falling to the surface.
Each of these processes contributes to the amount and size of rainfall we experience. Understanding them is vital to improving weather predictions, as well as for planning and responding to natural disasters.
The idea that raindrops are similar to tears is a myth that has been debunked through scientific research. Raindrops are actually much more complex than we often imagine and have a significant impact on our climate and environment. From their shape to their formation, every aspect of raindrops offers valuable insight into the natural processes on our planet.
