Question 1 of 15
What causes Earth's seasons?
Why: Earth's axis is tilted about 23.5 degrees, so each hemisphere leans toward or away from the Sun through the year.
Question 2 of 15
When is Earth actually closest to the Sun?
Why: Perihelion occurs in early January, during Northern Hemisphere winter, which proves distance is not the cause.
Question 3 of 15
What happens at the June solstice in the Northern Hemisphere?
Why: Around June 21 the North Pole tilts most toward the Sun, giving the hemisphere its longest daylight.
Question 4 of 15
What does 'equinox' literally mean?
Why: From Latin aequus and nox, equal night, when daylight and darkness are close to equal everywhere.
Question 5 of 15
When do meteorological seasons begin?
Why: Meteorologists use whole calendar months so seasonal statistics compare cleanly year to year.
Question 6 of 15
Why is the hottest weather usually weeks after the longest day?
Why: This seasonal lag means July and August usually beat June despite less daylight.
Question 7 of 15
What is the Tropic of Cancer?
Why: It marks the northern limit of the Sun ever reaching the zenith, reached at the June solstice.
Question 8 of 15
What happens above the Arctic Circle at the June solstice?
Why: The midnight sun shines continuously, while the Antarctic Circle experiences continuous darkness.
Question 9 of 15
When it is summer in the Northern Hemisphere, what season is it in Australia?
Why: The hemispheres are opposite because they tilt toward the Sun at opposite times of year.
Question 10 of 15
What does 'solstice' literally mean?
Why: From sol and sistere, referring to the Sun pausing in its seasonal drift before reversing direction.
Question 11 of 15
How often is the Sun directly overhead at the equator?
Why: At the equator the Sun passes through the zenith at both the March and September equinoxes.
Question 12 of 15
Why is day slightly longer than night on the equinox itself?
Why: Refraction lifts the Sun's image, so true equal day and night, the equilux, falls a few days off the equinox.
Question 13 of 15
What is the analemma?
Why: It results from Earth's axial tilt combined with its elliptical orbit.
Question 14 of 15
Which season generally has the most tornadoes in the United States?
Why: Spring brings the sharpest clash of warm moist Gulf air with cold air aloft, plus strong wind shear.
Question 15 of 15
Do the equinoxes fall on exactly the same date every year?
Why: The extra quarter day per year is why dates drift and why we add leap days to correct them.