Introduction to Earth Science

Introduction to Earth

• The lecture serves as an introduction to Earth science.
• It will cover fundamental concepts vital to the study of Earth.
• It will encompass the definition of Earth as a system, the environmental spheres, basic physical concepts, and Earth-Sun relations.

Earth as a System

• A system comprises interrelated components that are somehow related or organized.
• A landscape is the visible features of an area of land, including its landforms and their integration with natural or human-made features.

The Environmental Spheres

• The environmental spheres include the Lithosphere, Atmosphere, Hydrosphere, Biosphere, and Anthroposphere.

Lithosphere

• Describes the solid inorganic portion of the Earth.
• It is composed of rocks, minerals and other elements.
• It can be regarded as the surface and interior of the solid Earth.

Atmosphere

• Gaseous envelope of air that surrounds the Earth.
• Its boundaries aren't easily defined.
• It contains a complex system of gases and suspended particles that behave like fluids.

Hydrosphere

• Describes waters of the Earth.
• Water exists in various stores, including the atmosphere, oceans,lakes, rivers, soils, glaciers, and groundwater.

Biosphere

• Consists of all living things, plants, and animals.
• It is characterized by life in profusion, diversity, and ingenious complexity.

Anthroposphere

• Part of the Earth system that humans have created or modified for their own use and habitats.
• Includes everything related to human civilization, like culture, technology, built environments, and activities.

System Types

• Isolated systems: energy and matter cannot enter or leave the system.
• Closed systems: energy can enter or leave, but not matter.
• Open systems: both energy and matter can enter or leave the system.

Closed System Implications

• Earth is a closed system, which has two implications.
• The amount of matter in a closed system is fixed and finite; mineral resources are all we have for the foreseeable future.
• Changes in one part of a closed system will eventually affect other parts.
• Earth is a closed system, but its components are open systems where matter and energy can transfer between.
• Disturbances in one component of the Earth will result in changes in other components.

Box Models

• Box models are analogies that can be used to visualize how matter and energy move and change from one system component to another.
• Reservoir: the amount of matter or energy stored in the "box".
• Flux: the rate (amount per unit time) at which matter or energy is added to (source) or removed from (sink) reservoir.
• Steady-state: sources = sinks, no net change in the amount of matter or energy.
• Residence time in the steady-state: the time it would take to empty (or fill) the reservoir.

Feedback Loops

• Positive feedback: destabilizing, amplifies the original disturbance.
• Negative feedback: desirable, stabilizes and leads to a system that remains in a constant condition.

Basic Physical Concepts

• Includes matter, chemical elements, molecules, properties of matter, and forces.

Matter and Elements

• Matter: Substance occupying space that has mass (measured in g or kg); all matter on Earth is constructed of elements.
• Chemical element: Material that cannot be broken down or changed into another substance by chemical means.
• Atom: The smallest particle that exhibits the unique chemical characteristics of an element.

Molecules

• Molecules are combinations or arrangements of atoms.
• Examples include hydrogen (H2), oxygen (O2), nitrogen (N2), chlorine (Cl2), nitrogen oxide (NO), water (H2O), nitrogen dioxide (NO2), and carbon dioxide (CO2).

Properties of Matter

• Mass (m): Intrinsic property based on the molecular composition of matter.
• Mass remains constant as long as the amount of matter doesnt change, regardless of location.
• Mass is normally measured in grams (gr) or kilograms (kg).
• Volume (V): Property of matter related to space.
• Volume is a measure of the amount of space an object occupies.
• Volume will normally be measured in cubic meters (m³).
• Density (ρ): Property of matter related to both mass and volume.
• Density is defined as the quantity of mass found in a given volume, or mass per unit volume.
• Density can change: density increases when mass increases or volume decreases, and density decreases when mass decreases or volume increases.
• Buoyancy: The tendency of an object to float in a fluid.
• An object floats if its average density is less than the density of the fluid it's in.
• An object sinks if its average density is greater than the density of the fluid it's in.

States of Matter

• Gas: total disorder, much empty space, particles have freedom of motion and are far apart.
• Liquid: disorder, particles or clusters of particles are free to move relative to each other and are close together.
• Crystalline solid: ordered arrangement, particles are essentially in fixed positions and are close together.
• Solids generally have a higher density than liquids because they are more closely packed than liquids.
• Exception: liquid water's density is 9% higher than solid ice, which is why ice floats.

Force, Mass, and Weight

• Force: Mass of an object multiplied by the change in its velocity over time, or acceleration.
• Force is measured in "Newtons," where 1 N = 1 kg·m/s².
• Gravity: The force drawing all matter together.
• Objects with more mass exert a stronger pull on smaller objects.
• Gravity also depends on the distance between objects: smaller distances cause stronger gravitational pull.
• Weight: Force acting on an object under gravitational acceleration.
• Weight is calculated as W (kg m s¯²) = ρVg, where ρ is density and V is volume.

Pressure and Energy

• Pressure (P): Force per unit area (A), measured in "Pascals".
• 1 Pa = 1 newton (N) of force applied over an area of 1 square meter (m²).
• 100 Pa = 1 millibar (mb).
• Work: Done on a substance when it is pushed pulled or lifted.
• Energy: Capacity for doing work.
• Joule (J): Unit of energy
• Work: Force x Distance: Joule (J) = 1 Newton (N) x 1 meter (m)
• Power: Energy/Time: Watt (W) = 1 Joule (J) / 1 second (s)
• Intensity (FLUX): Power/Area: Intensity (Wm⁻²) = Watt (W)/m²

Types of Energy

• Kinetic energy: Energy due to motion.
• Potential energy: Energy stored by an object that can be transformed into another energy form
• Energy can neither be created nor destroyed, but it is converted in form or transferred between locations.

Heat and Temperature

• Heat Energy is a form of kinetic energy due to combined internal motion of atoms and molecules in a substance.
• Heat (symbol: Q) is energy and represents the total amount of energy possessed by the molecules and atoms in a piece of matter, is measured in Joules.
• Temperature is the measure of average internal motion, not total energy like heat.
• Absolute zero: 0 Kelvin (0 K), the temperature at which there is no internal energy.
• Heat depends on the speed of molecules, number of molecules and type of molecules in an object.
• Increases and decreases in temperature rely on adding and removing heat.
• Higher temperatures mean molecules move/vibrate/rotate with more energy.
• Temperature is not energy, but a measure of it.

Temperature Scales

• Fahrenheit (°F): °F = 1.8° C + 32
• Celsius (°C): °C = 0.56 (°F – 32)
• Kelvin (K): K = °C + 273

Origins of the Universe

• 13.7 billion years ago, all matter/energy in the Universe was concentrated into the size of an atom.
• Big Bang: The Universe began an incredible expansion, and matter, energy, space, and time came into being.
• Matter began to coalesce into gas clouds that became stars and planets.
• Solar system formed 4.5 billion years ago when Universe was 65% of its present size.
• Today, the Universe continues to expand outward.

Elements in the Universe

• Lighter elements (H, He) formed during the Big Bang.
• Heavier elements are formed in stars via fusion.
• 1H + 1H → 2He
• 2He + 2He → 4Be
• 4Be + 2He → 6C, etc...
• Solar wind: Stream of charged particles released from the Sun's outermost atmospheric layer, the corona and consists mostly of electrons, protons, and alpha particles.

Solar System Formation and Gravity

• Sun condensed from nebular clouds.
• Gravity: the mutual attracting force exerted by mass on all other objects.
• The life span of the Sun will allow it to keep Earth habitable for another ~ 500 million years.

Earth Formation and Structure

• Planet grows by collisions with smaller bodies.
• Kinetic energy transformed during each collision into heat energy.
• Heating of early Earth caused by both collisions and radioactive decay.
• Everything melted and a differentiation of matter by density began.
• Denser matter (iron, nickel) sunk to the center, forming the core; lower-density matter rose to form the crust.
• Lowest-density matter (gasses) was driven from the interior (outgassing).

Earth in the Solar System

• The Earth is 1 of 8 planets.
• It is not in a fixed point; it follows a cyclical pattern of movement.

Earth Stats and Figures

• Made up of Jovian solids, terrestrial liquids and gases.
• Age: 4.5 billion y/o
• Weight: 6,600,000,000,000,000,000,000 tons
• Rotation: 23 hrs., 56 mi., 4.09 sec.
• Revolution: 365 days, 6 hrs., 9 min., 9.53 sec.
• Diameter of the sun is 1,392,000 km (865,000 mi), or 109 Earths.
• Polar Diameter: 12,714 km (7,900 miles).
• Equatorial Diameter: 12,757 km (7,927 miles).
• Polar Circumference: 40,008 km (24,860 miles).
• Equatorial Circumference: 40,076 km (24,902 miles).
• Highest Land: Mount Everest, 8,850 m (29,028 feet).
• Lowest Land: Shore of Dead Sea, 396 m (1,299 feet) below sea level.
• Deepest: Pacific Ocean southwest of Guam 11,033 m (36,198 feet) and Av.
• Ocean Depth: 3,795 m (12,450 feet).
• Earth’s maximum relief is ~20 km.

Earth's Coordinates

• Cartesian coordinate system: Specifies each point uniquely in a plane with a coordinate pair or signed distances from the point to fixed perpendicular axes measured in the same units.
• Latitude: 0 to 90 degrees north/south of the equator.
• Longitude: 0 to 180 degrees east/west of the prime meridian.
• Angular measurements, in common units, from the center of the Earth in degrees, minutes, and seconds (1 ° = 60 ', 1 ′ = 60 “).
• Great circles: Planes through the center of a sphere diving sphere into two equal halves.
• Equator: The only “horizontal” (latitude) which is a great circle that divides the Earth into the Northern and Southern hemispheres.
• NOTE: Degrees of latitude remain at fairly consistent distances while longitude significantly changes north or south!

Earth’s Rotation

• Rotates West to East (counter clockwise); 360° in 23 hrs, 56 min, 4.09 sec.
• The edge dividing the daylight from night is called the circle of illumination.
• Earth’s rotation creates the apparent movement of the Sun across the horizon

Revolution

• Revolution: 365.242 days
• The Earth has an elliptical orbit, the Earths distant can vary with the sun annually(Perihelion and Aphelion).
• Axis in inclined at 23.5 deg with the ecliptic.
• Axis is a constant to the Polarity or North Star.

This lecture introduces Earth science, covering its fundamental concepts. The topics include defining Earth as a system, the environmental spheres, basic physics concepts, and Earth-Sun relations. Focus is on the Lithosphere, Atmosphere, Hydrosphere, Biosphere and Anthrosphere.