Australian bureau of meteorology admits to chemtrails - calls it 'chaff'.

"What appeared to be an ominous storm cloud rolling across the weather radar was actually a military aircraft tactic used to hide activity and confuse the enemy.

Known as chaff, it’s a radar countermeasure in which aircraft or other military targets spread a cloud of small, thin pieces of aluminium, metallised glass fibre or plastic. The radar-jamming material either appears as a cluster of targets on radar screens or overwhelms the screen with hundreds of returns, or “false echoes”."

https://www.news.com.au/technology/innovation/military/it-looks-like-rain-but-its-actually-secret-military-exercises/news-story/0bd86fdc0b62ded8c5a32d04d96d78eb