You can only observe it in a car – removed enough from your surroundings for the trick to work
yet close enough to believe.
Sometimes they’re called magnetic hills or mystery hills.
“The most important factor contributing to the illusion is a completely or mostly obstructed horizon. Without a horizon, it becomes difficult to judge the slope of a surface as a reliable reference is missing.”
What else is a mystery hill?
How much depends on an obscured horizon?
“The term ostension is also used by those who study folklore and urban legends to indicate real-life happenings that parallel the events told in pre-existing and well-established legends and lore.”
The ostension of a wedding.
The ostension that is marriage.
The gravity hill of love.