Dimensions of the Earth
Shape and Composition of the Earth
The Earth is close to being a perfect sphere.
The Earth bulges slightly at the equator and flattens slightly at
the poles.
Evidence of the Earth’s shape?
Ships “sink” when moving past the horizon
Satellite photographs
Moon phases and lunar eclipses
Nearly equal gravitational attraction of objects all over the
Earth’s surface.
POLES: slightly flattened
EQUATOR: slightly bulging
The Earth is composed of a series of spheres. Each sphere has a different composition of materials and is held together by gravity. The spheres of Earth are arranged from least dense (atmosphere)
to most dense (geosphere) depending on how close they are found to the Earth’s center.
AtmosphereThe layer of gases that surround the Earth
located above the Earth’s surface is known as the atmosphere.
The atmosphere is the least
dense of all the spheres
The atmosphere is composed of 78%
nitrogen,21% oxygen and 1% other gases
and aerosols – suspended solids and
liquids in the atmosphere.
Earth’s atmosphere is broken down into
smaller spheres (zones) with distinct
differences in air temperature and composition. The interface between these zones are called pauses.
RT = Pg. 14
Hydrosphere The layer of liquid water found at the Earth’s surface is known as the hydrosphere.
The hydrosphere consists of bodies of freshwater and saltwater found on
Earth’s surface including: oceans, lakes, rivers and
streams.
Mostof the hydrosphere(~
70%) is composed of
water (hydrogen/oxyg
en).
Lithosphere The layer of rock that forms the outer shell of the Earth is known as the lithosphere.
The lithosphere lies
beneath the atmosphere
and hydrosphere.
The uppermost section of the lithosphere is
the crust which is broken up into sections
known as lithospheric or tectonic plates.
RT = Pg. 1
Geosphere The region of the Earth between the crust and Earth’s center is known as the geosphere.
The geosphere is the most
dense of all the spheres
RT = Pg. 10
The geosphere is broken into zones
based on changes in density, pressure and temperature.