Earth, sun and moon InteractionsPresentation Transcript
EARTH , SUN, andMoonInteractions
How does what happens up there Affect what happens down here
Understanding Climate and Weather What?Why and How?
Guide Questions Why do we have night and day? How long is a day/a year? How does sunlight hit the Earth’s surface? (equator vspoles) Why is it warmer at the equator and colder at the poles? Why are there seasons? What is climate and what causes different climates? What is longitude and latitude and how are they related to climate?
What causes Night and Day?
Length of Day: http://www.cs.sbcc.net/~physics/flash/LengthofDay.swf
DAY AND YEAR
DAY AND YEAR Rotation earth’s spinning on its axis 1,600 km/hr (rate of spin at any point along the equator) Revolution movement of earth around the sun
Leap Year It actually takes the Earth a little longer than a year to travel around the Sun — 365 days, 5 hours, 48 minutes, and 46 seconds, to be exact. It was the ancient Egyptians who first figured out that the solar year and the man-made calendar year didn't always match up. It was the Romans who first designated February 29 as leap day That extra day was added to February because February used to be thelast month of the year http://www.chiff.com/a/leap-year.htm
When do we have leap years? a leap day happens in years only divisible by four, i.e., 1996, 2000, 2004 Another stipulation ruled that no year divisible by 100 would have a leap year, except if it was divisible by 400. Thus, 1900 was not a leap year ... but 2000 was! Go figure.
Leap Years When was the last leap year? 2008 When is the next? 2012
Number of Daylight Hours Every part of Earth gets about the same number of hours of daylight per year half a year of full daylight BUT, not received the same way EQUATOR: it is delivered evenly -- exactly half a day, every single day, throughout the year. POLES: it is delivered all at once -- half a year of daylight, and then half a year of darkness. MIDLATITUDES: it is delivered in greater or lesser amounts, throughout the year -- some days having more than half a day of daylight, but others, half a year later, having less than half a day, and the average, throughout the year, being half a day of daylight per day
AMOUNT OF SUNSHINE However, although the different regions receive the same number of hours of daylight, they do NOT receive the same amount of sunshine the amount of sunshine which is received over a certain amount of the ground depends upon how high the Sun is in the sky (the angle of the sun’s rays)
How sunlight hits the Earth’s surface
When sunlight shines from overhead (on left), one square foot of sunlight falls on one square foot of ground. When it shines at a shallow angle (on right), each square foot of sunlight spreads out over many feet of ground. http://cseligman.com/text/sky/climate.htm
Effect of How Sun Hits Earth Equator always warmer (tropical) Poles always colder (arctic)
REASON FOR THE SEASONS
Earth Motions: PRECESSION Precession – Earth’s axis maintains approximately the same angle of tilt, but the direction in which the axis points continually changes. Currently, the axis points toward Polaris. In the year 14,000, it will point toward Vega. By 28,000, it will point toward Polaris again.
SEASONS We have seasons because: The Earth’s axis is tilted 23.5o, so different locations receive different amounts of direct sunlight throughout the year.
March Equinox June Solstice December Solstice Sun September Equinox
FACTORS THAT AFFECT CLIMATE Axis or tilt of the Earth -length of day & seasons Latitude (sun angle) Elevation Precipitation (rain, snow, hail) Currents (wind, ocean)
What patterns do you notice with the colors?
Geography basics http://www.youtube.com/watch?v=95TtXYjOEv4 9 mins
How sunlight hits the Earth’s surface?
Peralta Colleges, Physical Geography
The latitude and longitude system Longitude lines run north-south and meet at the North and South Poles; also called meridians. Latitude lines run east-west and don't meet; also called parallels.
Latitude The latitude of a country is its angle above or below the equator. For example
North Pole - 90° North
South Pole - 90° South
Paris, France - 48° North
Sydney, Australia - 34° South
Latitude Paris Equator 48°
Latitude Some important lines of latitude include The Equator – 0° The Tropic of Cancer – 23.5° N The Tropic of Capricorn – 23.5° S The Arctic Circle – 66.5° N The Antarctic Circle – 66.5° S
Longitude The longitude of a country is how far around the earth it lies from London = 0 ° (Prime Meridian). For example Manila - 120° East New York - 74° West The time zones follow lines of longitude that are every 15° away from London
Longitude London New York
TIME ZONES Time zones: Every 15˚, changes by 1 hour
Climate change due to a country’s location
Latitude effect on seasonal change
precipitation levels (rainfall and snowfall)
average (and max, min) temperatures
cultural changes due to climate differences (e.g. S.A.D)
THE TIDES... What are they? The rising and falling of sea level twice each day.
Tides Tides are created by the gravitational force of the Sun and Moon. The Moon’s gravity pulls Earth along an imaginary line connecting Earth and the Moon. This creates bulges of ocean water (tides). The bulges remain aligned with the Moon, so that ocean levels rise and fall as the Earth rotates.
Why are there two each day?
The side of Earth facing the Moon feels a stronger gravitational attraction.
This creates two tidal bulges…One facing the Moon & the other on the opposite side.
Oceans facing Moon bulge because they are being pulled out from the Earth.
Oceans on opposite side bulge because Earth is pulled out from under them.
Sun has minimal gravitational effect on Earth but when Sun and Moon align, their gravitational pulls combine Spring Tides – larger tidal range; occur at new moon and full moon. Neap Tides – smaller tidal range; occur at 1st and 3rd quarter.