Venus' lightning similar to Earth's

Scientists have discovered that lightning mechanisms on Earth are very similar to those on Venus.

The rates of discharge, intensity and spatial distribution of lightning are comparable.

Findings will help scientists to understand the chemistry, dynamics and evolution of the atmospheres of the two planets.

The launch of Venus Express with its magnetometer, built by the Space Research Institute in Graz, Austria, has provided an opportunity to confirm the occurrence of lightning on Venus, and to study in detail its magnetic field at altitudes between 200 and 500km.

"Short strong pulses of the signals expected to be produced by lightning were seen almost immediately upon arrival at Venus, despite the generally unfavourable magnetic field orientation for entry of the signals into the Venus ionosphere at the altitude of the Venus Express measurements," said Christopher Russell of the University of California, USA.

As cloud particles collide, they transfer electrical charge from large particles to small, and the large particles fall while the small particles are carried upward. The separation of charges leads to lightning strokes.

This process is important for a planetary atmosphere because it raises the temperature and pressure of a small region in its atmosphere to a very high value, so that molecules can be formed, which would not occur at standard atmospheric temperatures and pressures.
 
Based on this, some scientists speculated that lightning may have helped life to arise on Earth.

"We have analyzed 3.5 Earth-years of Venus lightning data using the low-altitude Venus Express data (10 minutes / day). By comparing, the electromagnetic waves produced at the two planets, we found out stronger magnetic signals on Venus, but when converted to energy flux, we found very similar lightening strength," reported Russell.

It also seems that lightning is more prevalent on the dayside than at night, and happens more often at low Venusian latitudes where the solar input to the atmosphere is strongest.

"Venus and Earth are often called twin planets because of their similar size, mass, and interior structure. The generation of lightning is one more way in which Venus and Earth are fraternal twins," Russell said.

These results were presented by Russell at the European Planetary Science Congress, on September 23.