citybackpack.jpg — Steven Lewis stevenlewis — CC0 — https://commons.wikimedia.org/wiki/File:Backpacking_in_a_busy_city_(Unsplash).jpg
supercell.jpg — NOAA National Severe Storms Laboratory — Public domain — https://commons.wikimedia.org/wiki/File:Supercell-thunderstorm-in-Kansas.jpg
lightning.jpg — Mike Eliason, Santa Barbara County Fire Department's public information officer according to Twitter and CNN — Public domain — https://commons.wikimedia.org/wiki/File:Lightning_strikes_in_Santa_Barbara_2019-03-05.jpg
hallway.jpg — ChinaFlag — Public domain — https://commons.wikimedia.org/wiki/File:Boxwood_PS_Hallway_3.jpg
forest.jpg — Peter Heeling — CC0 — https://commons.wikimedia.org/wiki/File:Forest_sunrise.jpg
silhouette.jpg — freestocks.org freestocks — CC0 — https://commons.wikimedia.org/wiki/File:Silhouette_woman_standing_sunset_(Unsplash).jpg
fogsunrise.jpg — Ted Moravec — CC0 — https://commons.wikimedia.org/wiki/File:Foggy_Bohemia_sunrise_(52873160744).jpg
storm.jpg — M. Cristian-Ioan — Public domain — https://commons.wikimedia.org/wiki/File:Caraiman_in_dramatic_clouds_(2).jpg