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dcyphr | Small lightning flashes from shallow electrical storms on Jupiter

Abstract

Despite the limited images of lightning on Jupiter, many photos have been used to determine the properties of lightning on Jupiter. For the first time, very high resolution photos have been taken of lightning, which show a higher flash rate, faster flash duration, and more accurate HWHM values. Same of the lightning has an origin higher than liquid water exists, which causes scientists to reconsider the known mechanism of lightning generation.

Aims

This study aims to discuss the meaning of the new lightning data discovered on Jupiter, and possible therories explaining the data.

Introduction

The Juno’s Stellar Reference Unit (SRU) was designed to take pictures of dim stars, but instead recently captured 14 lightning bolts on Jupiter. The Juno’s Microwave Radiometer (MWR) was able to confirm the photos were of lightning. Due to the SRU camera’s properties, we were able to capture the highest resolution, most detailed photos of lightning ever on Juputer.

Results

With the new photos, we can estimate that the global flash rate is 15 times higher than previously predicted. The lightning on Jupiter mostly has similar optical energy compared to lightning on Earth, but some of the lightning has much smaller optical energy and faster flash rate than previously measured. 

 

The HWHM measurement is used to define the depth of lightning in the atmosphere. HWHM stands for half width and half maximum intensity. If the beginning of the lightning is closer to the center of the planet, it will expand in a circular and outward pattern through the atmosphere, so the HWHM will be larger.

 

The pressure of Jupiter is measured in bars, and decreases as the altitude increases. Interestingly enough, much of the lightning began at a very high bar level, where liquid water cannot exist. This forces scientists to rethink how lightning may be generated on Jupiter, because lightning generated on earth occurs via charge separation and requires both liquids and solids. 

 

One possible explanation is that frozen bits of ice are thrust upward to a high enough bar where they can mix with ammonia, creating a liquid that could fall and collide with other solid bits of ice lower down. This would be impossible on earth, but may be possible with the high amounts of ammonia in Jupiter’s atmosphere. 

A second possible explanation is that no water is necessary for lightning on Jupiter.

 

Recently on earth, it has been found that lightning can start in the environment of the middle of a very dense cloud, called anvils, if the altitude is high enough and the temperature is low enough. It is possible that Jupiter could have the same cloud anvil environment at the high bars we saw the lightning originating from.

At lower depths, there was some lightning recorded that could have mirrored how lightning is formed on Earth.

Discussion

These findings tell us that to understand how lightning is formed on jupiter, we need to think outside of the only temperature and pressure system we are familiar with here on earth. These theories suggest that ice is commonly thrust upwards in Jupiter. This may explain the data we have that says the ammonia levels in jupiter have been dropping -- since we can only measure the ammonia in the gas form, we may not have caught that the upward thrusted ice has been mixing with ammonia and therefore its gaseous form is being removed. With more images and data, we will begin to understand lightning and latitude on Jupiter.

Methods

Data from Juno’s Stellar Reference Unit and Juno’s Microwave Radiometer were analyzed to determine the properties of the lightning and storms captured on Jupiter.

Conclusion

The new photos we have of lightning and storms on Jupiter give great insight on the different temperature and pressure systems that may be able to generate lightning; more research will further this understanding.