Topic 2: Measuring the Earth

Size and Shape Earth’s shape is not a perfect sphere flat at the poles, bulging at the equator It’s true shape is an OBLATE SPHEROID

Models A Model is a way of representing the properties of an object A MODEL of the Earth is always shown as a PERFECT CIRCLE (globe)

How do we know the earth is round? Photographs taken from space As you watch a ship travel away from you, it appears to sink and not just fall off.

Outer Spheres of the Earth Atmosphere- gas layer Hydrosphere- water layer Lithosphere- solid/rock layer

Which Layer is Densest?

Spheres of the Earth Open your E.S.R.T. to page 1

Atmosphere The Atmosphere or gas layer is made mostly of…. Nitrogen and oxygen Page 14 of the E.S.R.T. shows the properties of the Atmosphere

Atmosphere These zones of the atmosphere are: Troposphere Stratosphere Mesosphere Thermosphere In between each layer is a interface known as a PAUSE

Please answer the questions on Page 1 of your Notes

1. 4600°C, 1.2 million atmospheres (+/- 0.2) Answers: 1. 4600°C, 1.2 million atmospheres (+/- 0.2) 2. oxygen 3. -90°C 4. 0°C 5. 12 km

Locating Positions on Earth’s Surface How does GPS locate positions on earth? Coordinate system- using 2 points to find a location Page 2

Latitude and Longitude

Finding the coordinates Always written as Latitude, Longitude Every degree is separated into 60 minutes Followed by a direction N, S, E, W ESM is 40°50’ N, 72°49’W

To get to the next line of Page 2 10 20 30 40 50 60 70 80 90 15 45 75 105 120 135 150 165 180 E F G H To get to the next line of latitude, you must move in which of two directions? Latitude Equator

10 20 30 40 50 60 70 80 90 15 45 75 105 120 135 150 165 180 E F G H North South

Latitude is measured and from the North South Equator

To get to the next line of longitude, you must move 10 20 30 40 50 60 70 80 90 15 45 75 105 120 135 150 165 180 E F G H To get to the next line of longitude, you must move in which of two directions? Prime Meridian

10 20 30 40 50 60 70 80 90 15 45 75 105 120 135 150 165 180 E F G H West East

Longitude is measured and from the East West Prime Meridian

On the coordinate system, plot the coordinates given in your notes: 10 20 30 40 50 60 70 80 90 15 45 75 105 120 135 150 165 180 E F G H D A B C

State the coordinates for each of the letters in the figure above: 10 20 30 40 50 60 70 80 90 15 45 75 105 120 135 150 165 180 E F G H 20°N, 75°E 65°N, 50°W 70°S, 15°E 10°S, 135°W

BASED ON THE ____________ Page 3 LATITUDE ALTITUDE BASED ON THE ____________ OF _______________ POLARIS

Latitude Latitude is the angular measurement in the northern hemisphere from the equator to the north star (Polaris) is equal to latitude in the northern hemisphere

LATITUDE = ALTITUDE

POLARIS CAN ONLY BE SEEN IN THE HEMISPHERE NORTHERN

Polaris with Time Traces

So…….. If I find the angle of Polaris to be 27° from my location what is my latitude? 27° North If I am in Manorville at 42°06’ N, 75°55’W. What is the altitude of Polaris? 42°

Polaris at Different Latitudes

25°N, 100°W Altitude of Polaris 25°

30°S, 100°E Altitude of Polaris Can't be seen!

80°S, 65°W Altitude of Polaris Can't be seen!

45°N, 105°E Altitude of Polaris 45°

LONGITUDE BASED ON EARTH’S ROTATION

LONGITUDE EACH HOUR, EARTH ROTATES 15° (360°/24hrs)

HOW MANY TIME ZONES?

HOW MANY TIME ZONES? 24 TIME ZONES 15° APART

People on the same line of longitude have the same Local Time

Example: Two students record a difference in local time of two hours. How many degrees of longitude apart are they? 15° x 2 hours = 30°

7pm THESE LONGITUDE LINES ARE 15° APART. If it is 2pm in time zone A, what time is it in time zone B? B 7 A 6 5 4 3 2 7pm

If it is 9pm at location X, what time is it at location Y?

If it is 11am at location W, what time is it at location Z?

What’s the highest longitude? Since a circle is 360o, Longitude increases East and West of the Prime Meridian from 0o at the Prime Meridian to 180o At the 180o you can find the International date line