The air feels a little bit different this time of year. Cooler, for sure, but also darker. Heavier, like someone hanging over your shoulder, breathing right in your left ear. Like maybe it’s Halloween, and you need to get in the mood with these four great books … Have you ever seen a ghost? Do you even believe they exist? If the answer is “not yet,” then you’ll want to read “Ghosted: A History of Ghost Hunting, and Why We Keep Looking” by Alice Vernon (Bloomsbury Sigma, $28).

For centuries — particularly the last two — humans have been fascinated with the idea that spirits exist and sometimes visit those of us who are on this side of the spectral plane. The Victorians were obsessed with them. There are lots of videos and TV shows you can watch tonight, if you want to see ghost hunters in action. What do skeptics say? And why do we keep looking for spirits of the dead?

Read this book and find out. Then reach for “American Spirits: The Famous Fox Sisters and the Mysterious Fad that Haunted a Nation” by Barb Rosenstock (Calkins Creek, $24.99). If you find the history in the Vernon book fascinating, this book takes things to the next level, with a long, deep look back nearly 200 years at what is arguably the beginning of the Victorian fixation with ghosts. It’s a solid book with photos and reprinted documents that just add to the Creep Factor.

Ghosts, of course, don’t just appear. They haunt, too, and “ America’s Most Gothic: Haunted History Stranger Than Fiction” by Leanna Renee Hieber & Andrea Janes (Kensington, $29) shows you the many ways that ghosts can spook you.

Broken up into several different segments, this book is wide and comprehensive as it takes you on a voyage through historic buildings and everyday homes, into rooms and wide-open spaces, through family lineages and into family crypts and, of course, there are curses. This is a fun book filled with stories that practically beg to be re-told around a campfire next summer.

And finally, if you’re planning on spending time on the water this winter, you may think again after you’ve read “The Book of Sea Monsters: Leviathans of Literature” by Prema Arasu (Bloomsbury / Adland Coles, $35). It’s a gorgeous coffee-table book full of photos, poems, legends, and tales of what’s beneath the waves that you can’t see. Some of the creatures in here are real. Some, well, you need to read. This is a great book for amateur cryptozoologists who love literature.

Now, if these four books don’t satisfy your craving for ghosts and monsters this fall, then head to your favorite library or bookstore and ask the staff to scare you with something good. They’ll have all kinds of books to suggest for you — books about spirits, sea serpents, cryptid creatures and real monsters. Stories with photos, stories that are obviously not true and some that, well, decide for yourself by finding a book with an air of total spookiness …

— The Bookworm Sez