Blue cloud over city

[Sangoma]

I'm sure that this has been answered somewhere, but what is the blue cloud/fireworks or whatever that sometimes comes over a city? I does not appear to be the normal 'We love the ...' celebrations.

[Jaybe]

You have units in the city which are eligible for promotions.

[Sangoma]

Thanks!

[Bkeela]

Fireworks indicates the 'We Love Leader' day. It reduces maintenance I think.