Lightning, explained

Lightning is the rapid flow of electricity between two oppositely charged regions in the atmosphere. The air surrounding the flow is superheated to up to five times the surface temperature of the sun, producing a bolt of plasma—atoms stripped of their electrons—that flashes intensely. The rapid expansion of this heated air generates a shockwave, which is heard as thunder.

Within storm clouds, collisions between updrafts of water droplets and ice crystals and downdrafts of graupel—soft hail—transfer electrons from rising to descending matter (watch visualization). Positive and negative charge builds at the top and bottom of clouds, respectively, until the electric potential difference becomes stronger than the insulating properties of air. An electrical discharge between the regions produces lightning as electrons rush through the air like a static shock, restoring charge balance (watch in slow motion).

While most lightning occurs within or between clouds (explore types), the potential can induce a net positive charge on Earth's surface below. If a filament of descending, negatively charged air meets a tendril of positively charged particles rising from the surface, cloud-to-ground lightning is produced (see visualization). Tall objects such as trees and buildings facilitate this meeting, making them more prone to lightning strikes.

Although associated with thunderstorms, the charge separation driving the 8 million lightning strikes that occur on Earth daily can occur during other extreme weather events (e.g., hurricanes, blizzards) and volcanic eruptions.

Also, check out ... 

> On average, every in-service airplane is struck by lightning once a year. (Read)

> Venezuela's Lake Maracaibo is considered the world's lightning capital. (Read)

> Where does the color of lightning come from? (View)

> Why does lightning zigzag? (Read)

Explore everything else we've found on lightning. 

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What are comets?

Comets are celestial objects composed of frozen gases, rock, and dust. They are characterized by two tails as they orbit near the sun, whose radiation and solar wind vaporize and push gas and dust away from the comet (see visualization). Comets serve as frozen archives of early solar system chemistry, and some models suggest they played a crucial role in bringing water to Earth during its formation (learn more).

Most comets come from two regions of leftover material from the formation of the sun and planets: the Kuiper Belt—a disc of material beyond Neptune, approximately 20 times wider than the asteroid belt—and the Oort Cloud—a spherical shell of icy objects orbiting between 5,000 and 100,000 times the Earth-sun distance. Minor gravitational disruptions can bring comets in these regions toward the inner solar system on highly elliptical orbits. Those originating from the Kuiper Belt can have orbits that repeat with periods of less than 200 years, while those from the Oort Cloud may have periods of about a million years. (see visualization).

Comets are named after the person, observatory, or mission that discovered them following a coded naming system developed by the International Astronomical Union. For example, I3/ATLAS was identified by the Asteroid Terrestrial-impact Last Alert System and is the third interstellar comet—from beyond the Oort Cloud—ever observed.

Also, check out ... 

> Shooting stars are fragments of asteroids and comets. (Watch)

> Twenty years ago, the Stardust mission returned comet samples to Earth. (View)

> The mission to successfully land on a comet. (Watch)

> The history of Halley's comet. (Read)

Explore everything else we've found on comets. 

OpenAI, 101

OpenAI is generally considered the most influential company at the forefront of the artificial intelligence boom. Led by CEO Sam Altman, it burst into the public consciousness in late 2022 with the release of the generative AI chatbot, ChatGPT. By February 2023, it had become the fastest-growing consumer app in history with a reported 100 million monthly active users.

The company was conceived as a nonprofit that would counter Google in the race to achieve systems with human-level cognition (learn more). However, three years after it launched in 2015—amid rising computing costs and a loss of funding from Elon Musk—it adopted a structure in which the original nonprofit oversaw a for-profit arm.

A tumultuous four-day span in 2023 saw the nonprofit board fire and reinstate Altman for alleged clashes between their altruistic philosophy and his vision for artificial general intelligence. Since then, he has led OpenAI to launch versions of generative image and video tools—DALL-E and Sora, respectively—and its version of the App Store, which provides GPT agents.

Also, check out ... 

> Before ChatGPT, OpenAI competed in esports. (Watch)

> Fair use may shield OpenAI from potential copyright violations. (Listen)

> Explore a gallery of creations from OpenAI's text-to-image generator. (View)

> "Airhead," the short movie created by Sora and post-production FX. (Watch)

Explore everything else we've found on OpenAI. 

Science Spotlight

Like all great scientists, we love spending time researching the latest scientific breakthroughs, tech releases, engaging explainers, and the connections between science and society that are making headlines. Here's what we found this week.

> Hydrofluorocarbons broken down by plasma and water interface

Yale Engineering | Staff. Previous efforts to destroy these greenhouse gases required high-temperature facilities and risked producing highly toxic hydrofluoric acid. The new energy-efficient method boasts a high conversion rate, can be converted into a portable system, and neutralizes any acid produced. (Read)

> Research suggests deer communicate through photoluminescent signals

UGA Today | Savannah Peat. Rubs on trees and scrapes on the ground—originating from forehead gland secretions and urine, respectively—were found to glow under ultraviolet light, which is most visible to deer at night when not washed out by sunlight. The glow may serve as a communication tool during mating season. (Read)

> Less than 20% of the total US river length is protected from human activities

UW News | Gillian Dohrn. A review found that most existing river protections are merely byproducts of land-based measures. Movement across borders, through ecological zones, and between public and private lands has led to inconsistent laws and regulations aimed at protecting against rising biodiversity loss. (Read)

> Linear number board games can strengthen young children's math skills

University of Oregon | Staff. A review of 18 studies that included over 1,700 children in pre-K to grade 2 showed that skills such as counting, identifying, and comparing numerals improved in games where players move pieces along a straight numbered path. Benefits may be seen with just a few 10-minute sessions. (Read)

> Lightning: Explore stunning lightning photography from the Grand Canyon. (View)

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Best of the Week

We curate hundreds of resources into 1440 Topics each week. Here are some of our favorites from the world of science and technology.

Read:

> A photo essay of the remarkable scale of China's renewable energy rollout.

> How algorithms make things more expensive through game theory.
> What it's like to live with a brain that doesn't feel fear.
> Fixing the blurry vision on the James Webb Space Telescope using AI.

Listen:

> The science behind headaches.

> The challenges of making appetizing food for astronauts.
> Examining scientific studies that assess the impact of seed oils.

Watch:

> How infinities having different sizes nearly broke mathematics.

> Exploring the technological applications of birthstones.

> Why airplanes don't fly in straight lines.

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