Summer is the warmest season of the year and starts at the summer solstice and runs till the autumnal equinox. The word summer derives from Old Norse sumar, but ultimately is from Proto-Germanic. By the late 1500s to early 1600s, it locked into its current spelling. The term midsummer actually refers to the day of the summer solstice as well as the "middle of summer." Its formation was patterned on words like midday, midnight, and midwinter.
Bonfire comes from the words bone and fire, referring to an open-air burning of bones or funeral pyre. The Oxford English Dictionary describes the use in Scotland of the form bane-fire and also to the annual midsummer banefire or bonfire in the burgh of Hawick, for which bones were collected and stored regularly until around 1800. Lighting bonfires was one of the most universal of ancient midsummer rites and one that still survives in some northern European countries. The solstice bonfires were believed to prevent cattle disease and were also associated with human courtship and fertility.
The phrase dog days is said to have originated in Roman times as canicularis dies, 'days of the dog,' referring to the dog star Sirius or Procyon. The Romans thought the rising of the most brilliant star of the constellation Canis Major contributed to the heat of summer.
The word humidity is from Latin humidus, from humere 'to be moist.' Humidity was found in English c 1400.
The solstice is one of the two times of year when the Sun's apparent path is farthest north or south from the Earth's equator. In the Northern Hemisphere, the summer solstice is on June 21 or 22, the longest day of the year. The situation is exactly the opposite in the Southern Hemisphere, where the summer solstice is on December 21 or 22. The word solstice is from Latin solstitium, from sol 'sun' and sistere 'to stand still,' as it is regarded as a point at which the Sun seems to stand still. The word was first used in English around 1250.
Though modern observances of the summer solstice are rare, there were celebrations in ancient times in Europe, the British Isles, China, Egypt, North Africa, and Scandinavia. These include the celebration in ancient Egypt at the Temple of Amen-Ra at Karnak, starting around 3700 B.C.E., where a beam of light would illuminate a sanctuary in the temple's interior for about two or three minutes on the day of the solstice. A similar phenomenon was observed at Stonehenge in southwest England. If one stands at the center of the monument and faces northeast along its axis, the 35-ton Heel Stone appears 256 feet away, marking the approximate place on the horizon where the sun rises on the summer solstice. Astronomers have discovered at least two dozen other solar and lunar alignments that the ancient builders of Stonehenge incorporated into its structure.
Vacation is a word coming from Latin vacation/vacatio, from vacare 'to be free, empty; to be at leisure.' Around 1395, this term entered Old English, meaning 'rest and freedom from any activity.'
