Weather and climate: Weather and climate By ASD When is …: When is … Hot I wear my______________ Rainy I wear my_____________ Cloudy I wear my ____________ Sunny I wear my ____________ Solstice: Solstice Hence it necessarily follows that the equinoxes and solstices seem to anticipate their timing, not because the sphere of the fixed stars moves to the east, but rather the equatorial circle moves to the west, being at an angle to the plane of the ecliptic in proportion to the declination of the axis of the terrestrial globe. Equinox: Equinox As the Earth travels around the Sun in its orbit, the north to south position of the Sun changes over the course of the year due to the changing orientation of the Earth's tilted rotation axes. The dates of zero tilt of the Earth's equator correspond to the Spring Equinox and Autumn Equinox. What are Equinoxes? : What are Equinoxes? Equinoxes occur when the axis of rotation of the earth (i.e. the line form the N to S poles) is exactly parallel to the direction of motion of the earth around the sun. This happens on just two days of the year, the spring and autumn equinoxes. This means that day length is exactly the same (12 hours) at all points on the earth's surface on these days (except right at each pole, where it will be about to change from permanent light to dark, or vice versa). Where does the name Equinox come from?: Where does the name Equinox come from? The name is derived from the Latin aequus (equal) and nox (night), because at the equinox the night and day are nearly equally long. How many times a year does a Equinox occur?: How many times a year does a Equinox occur? Equinoxes occur twice a year. The Autumn Equinox is the first day of the autumn season and occurs when the sun passes the equator moving from the northern to the southern hemisphere. The North Pole begins to tilt away from the sun. Day and night have approximately the same length. Autumnal equinox is near 22 September. The posh name for the Autumn Equinox is Autumnal Equinox The Spring Equinox The Spring Equinox is the first day of spring season and occurs when the sun passes the equator moving from the southern to the northern hemisphere. The North Pole begins to lean toward the sun again. Day and night have approximately the same length. Spring Equinox is near 20 March. The posh name for Spring Equinox is Vernal Equinox . Did you know?: Did you know? Equinoxes do not always occur on the same day each year, and generally will occur about 6 hours later each year, with a jump of a day (backwards) on leap years. Why do the equinoxes not always occur on the same day each year? The reason is due to the time the Earth takes to go around the Sun and our calendar. The Earth takes approximately 365.25 days to go around the Sun, yet our year is 365 days. Every 4 years, we have a leap year where another day is added to our calendar to make up for the 4 missing quarters. It is important to do this so that there is not a gradual drift of date through the seasons. For the same reason the precise time of the equinoxes are not the same each year. Weather happens at a particular time and place.: Weather happens at a particular time and place. Monday was hot, the sky was blue. Today it rained a trickle. Last week it snowed for two days straight. The weather is totally fickle! WEATHER: WEATHER Weather. It keeps you guessing. It makes every day an adventure. Whatever the weather is doing now, it’s probably going to be doing something else in a matter of hours. Weather also can vary abruptly from place to place. Sometimes the places are very close together. It could be raining at your house, but dry at school a few blocks away. PowerPoint Presentation: Meteorologists are scientists who study weather and weather prediction. With lots of high-tech tools, including the GOES satellites and radar and other ground-based instruments, meteorologists can give us a good idea of what the weather will be like for a few days in the future. Climate is regional and long-term: Climate is regional and long-term Climate is the bigger picture of temperatures, rainfall, wind and other conditions over a larger region and longer time. PowerPoint Presentation: Climate scientists (called climatologists) have sorted Earth’s regional climates into categories, or zones, based mostly on average temperatures and precipitation. These are the characteristics that determine whether a region is a tundra, a desert, or a rain forest. PowerPoint Presentation: The primary cause of a region’s climate is its latitude. At and near the equator (low latitudes), the Sun’s ray’s hit Earth’s surface almost head-on all year long. At the Poles (high latitudes), the sunlight hardly reaches the surface at all half the time, and when it does, it passes through the atmosphere at a steep angle. In the mid-latitudes, the climate is more moderate, with the angle of the Sun and length of day changing throughout the seasons. Here’s a map that shows Earth divided up by climate zones. : Here’s a map that shows Earth divided up by climate zones.