birta.

light, brightness

to show, to reveal

to publish

to become bright, to dawn

Það birtir.

Það birtir í austri.

to cause to break, to cause to dawn (of the day) [with preceding accusative ‘day’] (idiomatically translated as “break”, with the accusative object as the logical subject)

Við leggjum af stað þegar daginn birtir.

to cause to clear up, to cause to abate (of the weather) [with usually preceding accusative ‘weather phenomenon’] (idiomatically translated as “clear up” or “abate”, with the accusative object as the logical subject)

Hriðina birtir.

to cause to clear up (of fog, specifically) [with preceding dative ‘fog’] (idiomatically translated as “clear up”, “clear”, or “lift”, with the dative object as the logical subject)

Þokunni birtir.

for there to be a lighting up (becoming visibly happy) [with það ‘dummy subject’ and yfir (+ dative) ‘person lighting up’] (idiomatically translated as “light up”, with the dative prepositional object as the logical subject)

Það birti yfir henni þegar ég kom.

to appear