Subtitles section Play video Print subtitles This is Mike Petrucelli with the National Weather Service office in Medford, Oregon with a video on the Spring Equinox. With the recent change over to Daylight Savings Time and the warmer weather, you may be wondering when the first official day of spring is and what that means for the weather in our area. This graphic shows the earth’s tilt in its orbit around the sun. This tilt leads to our changing seasons and the amount of daylight through the year. We are currently moving from the Winter Solstice toward the Spring Equinox. Our Spring Equinox will occur at 4:02am on March 20th. The first days of spring and fall are referred to as equinoxes because there are nearly 12 hours of day and 12 hours of night throughout the northern and southern hemispheres. As you can see in the picture, the sun angle is 90 degrees at the equator at solar noon. Solar noon is the time when the sun is at its highest point in the sky for the day. These images show the amount of daylight expected across the globe on the first day of summer, winter and spring and fall. Since Medford is near 42 degrees north latitude, daylight will be near 12 hours on the first day of spring, increasing to 15 hours and 17 minutes on the first day of summer. Daylight then decreases back to near 12 hours by the first day of fall until it bottoms out at 9 hours and 4 minutes on the first day of winter. This figure shows the path the sun takes across the sky during the spring and fall, winter and summer. The sun takes a lower path in winter and increases each day until it reaches its highest point on the first day of summer. This day is also known as the Summer Solstice. This image shows where the sun angle is at solar noon in the winter, spring/fall and summer in Medford. In the winter, when the sun angle is lower, the mountains block more direct sunlight keeping the valleys cooler. As the sun angle gets higher, more energy is concentrated over the same area allowing the surface and atmosphere to heat up more. There is also less blockage from the mountains in the valleys allowing them to heat more. What does this mean for our weather as we move into spring and summer? Warmer days and less fog. We hope you’ve enjoyed this brief educational video on what the Spring Equinox means. Here are several websites you can use to stay up to date on the latest forecast. Thank you for listening.
B1 equinox winter daylight sun summer day Spring Equinox 2013 650 47 Bing-Je posted on 2013/12/10 More Share Save Report Video vocabulary