This struck me because it’s a rare sight, skies are rarely tar-black in or near cities. But this is Barcelona and perhaps the emptiness of the sea at night allows some of its overarching sky to seep into the city’s airspace and blacken it like ink.
‘It was a cold night, with an icy wind and tar-black skies.’
Source: Carlos Ruiz Zafón, The Shadow of the Wind, trans. Lucia Graves (London: Phoenix, 2012), p. 84