Aim: What is the reason for the seasons? Seasons animation Seasons animation.
The Seasons
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The Seasons
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The Seasons. The reason for the seasons…. There are three reasons earth has its seasons: it has a 23.5 degree tilt, it rotates on an orbit, and its North Pole always points in the same direction. YOU NEED ALL THREE FOR THE SEASONS TO OCCUR!!. Reason # 1 : Have you ever wondered why??. - PowerPoint PPT Presentation
Transcript of The Seasons
The SeasonsThe Seasons
The reason for the seasons….
There are three reasons earth has its seasons: it has a 23.5 degree tilt, it rotates on an orbit, and its North Pole always points in the same direction. YOU NEED ALL THREE FOR THE SEASONS TO OCCUR!!
Reason # 1 : Have you ever wondered why??
…the Earth on a globe is tilted?
Earth’s Tilt The earth’s axis is not straight up and down, instead it leans at a 23.5-degree angle.
Earth’s Axis
Axis of rotation- An imaginary line going from the north pole to the south pole. The earth spins on this.
The Earth’s tiltBecause the
Earth is tilted at a 23.5 degree angle, it has different amounts of sun hitting each section.
Notice that the Northern Hemisphere has much more sun light.
Indirect vrs. Direct sunlight
The area of the Earth that receives the most direct sunlight experiences summer.
The area of Earth that receives indirect sunlight experiences winter.
The area that has the sunlight distributed evenly experiences either fall or spring.
Summer
In the Northern Hemisphere the sun is directly hitting it during June, so it is summer.
What season is it in the Southern Hemisphere in June?
WinterDuring
December, in the Northern Hemisphere, the sun is hitting at an angle, so it is winter.
Can you tell where it is winter on these globes?
The sun’s angle
Because the Earth is on an angle, the sun sits lower in the sky during the winter. Because of this Earth receives less daylight and the days are shorter.
SummerDuring the summer
the sun is much higher in the sky so the days are much longer and warmer. The more sun you have the warmer you are!
Reason #2 :Earth’s orbit or revolution.
Without Earth orbiting the sun, there would not be different seasons. Take a look.
As the Earth Revolves
As Earth revolves around the sun, different parts of it are exposed to different amounts of sun.
If the Earth did not revolve around the sun, it would stay one season all the time.
If the Earth did not revolve around the sun, what season would it always be in the US?
Reason #3
The North Pole is always pointing in the same direction, towards Polaris (The North Star).
Sooo….
Since the axis is always pointed towards Polaris, it will not tip back around toward the sun.
Direct sunlight
Direct sunlight
Notice that the northern axis is pointed toward the sun.
Notice that the southern axis is pointed away from the sun.
Notice that neither axis is point toward or away from the sun.
What would happen if the Earth wobbled on it’s tilt?
What about Spring and Autumn?
Why do we experience Spring and Autumn?
We experience Spring and Autumn because as the Earth moves around the sun, the axis does not point toward the sun at all. So the angle of the of the sun is distributed evenly across Earth.
Equinoxes
Equinoxes : Mark an equal amount of day and night in both hemispheres. The Earth’s axis is not pointed toward the sun, so the Earth is receiving an equal amount of sunlight throughout.
Northern hemisphere: Spring Equinox: About
March 20: Autumnal Equinox: About
September 22
Solstices Winter solstice: December 22 in the Northern
Hemisphere. This marks the shortest day of the year when the Northern hemisphere is receiving the least amount of direct sunlight.
Summer solstice: June 21-22 in the Northern
Hemisphere. This marks the longest day of the year when the Earth is receiving the most amount of direct sunlight.
Did you know??? That the sun is actually
closer to Earth in the winter than in the summer?
It is…but only in the Northern hemisphere.
Because of the Earth’s elliptical orbit, the sun is actually closer to the Earth in the winter and farther away in the summer.
The Southern hemisphere is opposite.
The seasons have almost nothing to do how close the sun is to the Earth!!!
It is all about the angle!
The Equator
Countries near the equator do not experience the four seasons the same way we do in Utah.
Ecuador is near the equator and it stays warm all year because the angle of the sun stays the same.
Earth’s Equator
The Equator is an imaginary line drawn around the center of the Earth. It is of equal distance from the North and South Poles.
Rotation Versus Revolution Rotation: When a
planet or moon turns all the way around or spins on its axis one time.
Revolution: The circling of one object around another object in space. A planet revolves around the sun. A moon revolves around a planet.
Rotation, revolution
OrbitAn orbit is the
path that a planet travels as it goes around the sun.
Without our orbit we would not have the different seasons.
Las estaciones
Las razones de las estaciones
La razón numero uno. (#1)
La tierra tiene una inclinación de 23.5 grados.
23.5 grados
La tierra está rotando en su propia eje en un ángulo de 23.5 grados.
La razón numero dos. (#2)La tierra está orbitando
el sol.
El equinoccio otoñoEl 22/23 de septiembre
El equinoccio primaveraEl 20/21 de marzo
El solsticio de veranoEl 22/22 de junio
El solsticio de inviernoEl 22/22 de diciembre
La razón numero tres (#3)
El eje norte siempre está señalado a la estrella Polar.
Los equinoccios El equinoccio es la
época del año en que, por hallarse el Sol sobre el ecuador.
Los días y las noches son iguales en toda la Tierra.
Los solsticios
Es aquel instante en que el Sol se halla en uno de los dos trópicos.
Durante el solsticio de invierno, el día dura menos que la noche.
Durante el solsticio de verano, el día dura más que la noche.
Los equinoccios y solsticios
El equinoccio otoñoEl 22/23 de septiembre
El equinoccio primaveraEl 20/21 de marzo
El solsticio de veranoEl 22/22 de junio
El solsticio de inviernoEl 22/22 de diciembre
Los hemisferiosEl hemisferio
norte es la mitad superior de la tierra.
El hemisferio sur es la mitad inferior de la tierra.
Los Polos
El polo norte
El polo sur
El ecuador
El ecuador es el área alrededor del planeta que se encuentra a la misma distancia del punto que está más al norte y del que está más al sur en la Tierra.
El invierno
Durante el invierno los días son cortos y fríos.
El eje no está señalado al sol.
El invierno
Hace frío.
Está nevando.
La primavera
Durante la primavera ni el eje norte ni el eje sur está señalado al sol.
La primavera
Hace fresco.
Está lloviendo.
El verano
Durante el verano el eje está señalado al sol.
El verano
Hace calor.
Hace sol.
Hace buen tiempo.
El otoñoDurante el otoño ni
el eje norte ni el eje sur está señalado al sol.
El otoño
Hace fresco.
Hace viento
