How is Sunlight Changing? Mornings in North America (Back to Sunlight Observation) If your students are tracking sunrise and sunset times, they may have noticed these things this month: The sun continues to make a comeback, and daylength is changing more quickly. Days continue to get longer and warmer. Why? The strongest rays of the sun hit north of the equator in the spring. After the summer solstice (around June 21), days slowly get shorter and the sun appears to head south again. The sun doesn't actually move, but it appears to because of Earth's tilt. Our hemisphere tilts toward the sun in the summer and away from the sun in the winter. The orange circle shows where the sun's most direct rays hit Earth in each season. Why does all this matter? All seasonal changes – temperature, plant growth and life cycles, animal migrations, and so on – are driven by changes in the amount of available sunlight (called daylength or photoperiod) and its intensity (related to the angle at which it strikes the Earth). Shadows Change, Too! Are your students measuring the length of an object's shadow at the same time each week or month? They should begin to notice that the shadow continues to get shorter as the sun appears higher in the sky. (The rays begin to the Earth more directly.) Facebook Pinterest Twitter © 1997 – 2019 Journey North. All rights reserved.