Oceanography and Meteorology: An Introduction

Posted on Sep 3, 2024 in Geology

Oceanography

Composition of Seawater

Seawater is composed of 3.5% salt, with the remaining percentage being water. Salinity is measured as 35 parts per thousand. The most abundant dissolved components in salt are sodium and chlorine.

Ocean Bathymetry

Ocean bathymetry is the measurement of ocean depths and the charting of the shape of the ocean floor. It is measured by sending outgoing signals from a boat and reading the reflected signals from the ocean floor.

Abyssal Plain

The abyssal plain is the deep ocean basin.

Continental Shelf

The continental shelf is an underwater landmass that extends from a continent, resulting in an area of relatively shallow water known as a shelf sea.

Black Smokers

Black smokers are hydrothermal vents along the mid-ocean ridges where hot waters (up to 300 degrees Celsius) with dissolved minerals flow from vents.

Atolls

Atolls are ring-shaped coral reefs that include a coral rim encircling a lagoon partially or completely.

Currents

  • Tides cause surface waters to move.
  • Trade winds cause surface currents.
  • Density-driven variations from temperature (warm water rises, cool water sinks) and salinity variation (excess evaporation = increased salinity and density, causing water to sink).

Coriolis Effect

The Coriolis effect influences the direction of currents. Deflection is clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere.

Shoreline Processes

Ocean Circulation

Ocean circulation refers to the large-scale movement of waters in the ocean basins. Winds drive surface circulation, and the cooling and sinking of waters in the polar regions drive deep circulation.

Upwelling

Upwelling is the process in which deep, cold water rises toward the surface.

Tides

Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon and the Sun and the rotation of the Earth.

Waves

Waves are oscillations accompanied by a transfer of energy that travels through a medium (space or mass).

Longshore Currents

Longshore currents occur when water and sand move onshore at an angle from wave action. As the energy of the wave is expended, the water and sand flow back downslope, resulting in the net movement of sand along the beach. This is caused by waves hitting the beach at an oblique angle.

Meteorology

Composition of the Atmosphere

The atmosphere is composed of 78% nitrogen (N2) and 21% oxygen (O2). It also contains other elements and compounds, trace elements, and water vapor.

Structure of the Atmosphere

  • **Temperature:** In the lowest layer, temperature decreases with altitude.
  • **Pressure:** Pressure decreases with elevation.
  • **Moisture Content:** Moisture content decreases with elevation because cold, low-pressure areas hold less moisture. The Earth’s surface is the source of most water.

Reasons for Seasons

The tilt of the Earth results in less energy from the sun per unit area hitting the Earth’s surface in winter and more in summer (variable heating dependent on latitude). It also causes different lengths of days. Lastly, there is more absorption and reflection of solar energy by the atmosphere in the polar regions because of the low angle of the sun’s rays.

Electromagnetic Radiation

Electromagnetic radiation consists of waves (or their quanta, photons) of the electromagnetic field, propagating (radiating) through space, carrying electromagnetic radiant energy.

Greenhouse Effect

The greenhouse effect is the process by which radiation from a planet’s atmosphere warms the planet’s surface to a temperature above what it would be without its atmosphere.

Global Warming

Global warming is the rapid increase of carbon dioxide (CO2) and other greenhouse gases in the past century due to the burning of fossil fuels and other industrial processes.

Weather vs. Climate

**Weather:** The condition of the atmosphere at a particular place over a short period of time.

**Climate:** The average or long-term weather and atmospheric conditions of Earth, a region, or a specific location. Classification includes average weather statistics, paleo-records, and numerical modeling of atmospheric circulation.

Atmospheric Processes

  • **Rotation:** The spinning of Earth on its axis.
  • **Revolution:** The movement of Earth around the Sun.
  • **Radiation:** Electromagnetic waves that directly transport energy through space.
  • **Conduction:** The transfer of energy through matter from particle to particle.
  • **Convection:** The transfer of heat by the actual movement of the warmed matter.
  • **Precipitation:** Any product of the condensation of atmospheric water vapor that falls under gravity.
  • **Condensation:** The change of the physical state of matter from a gas phase into a liquid phase.
  • **Evaporation:** A type of vaporization of a liquid that occurs from the surface of a liquid into a gaseous phase that is not saturated with the evaporating substance.
  • **Adiabatic Cooling:** The process of reducing heat through a change in air pressure caused by volume expansion.
  • **Latent Heat:** The energy stored or released during a change in state.
  • **Humidity:** The amount of water vapor present in the air.
  • **Atmospheric Circulation:** The large-scale movement of air by which heat is distributed on the surface of the Earth.
  • **High and Low-Pressure Systems:** High-pressure systems are cool and dry from high elevation and descending (denser than surrounding air). Air warms from adiabatic heating, resulting in good (clear/dry) weather. Low-pressure systems are warm and moist from low elevation and rising (less dense than surrounding air). The air cools from adiabatic cooling, resulting in bad (cloudy/rainy) weather.
  • **Air Pressure:** The pressure exerted by the weight of air above.
  • **Wind:** The flow of gases on a large scale.
  • **Gradient:** A physical quantity that describes which direction and at what rate the pressure changes the most rapidly around a particular location.
  • **Air Masses:** An immense body of air characterized by a similarity of temperature and moisture at any given altitude. When air moves out of its region, it carries those temperature and moisture conditions elsewhere and eventually affects a large portion of a continent.
  • **Fronts:** The boundary separating two masses of air of different densities.

Severe Weather

  • **Tornadoes:** A rapidly rotating column of air that spins while in contact with both the surface of the Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud.
  • **Hurricanes:** A storm with a violent wind, in particular, a tropical cyclone in the Caribbean.
  • **Thunderstorms:** A storm characterized by the presence of lightning and its acoustic effect on the Earth’s atmosphere, known as thunder.
  • **Saffir-Simpson Scale:** Classifies hurricanes into five categories distinguished by the intensities of their sustained winds.

Astronomy

The Solar System

  • **Planets:** A celestial body moving in an elliptical orbit around a star.
  • **Origin of the Solar System:** Formed when a cloud of gas and dust in space was disturbed, maybe by the explosion of a nearby star (called a supernova).
  • **Earth’s Moon:** A natural satellite that orbits Earth.
  • **Asteroids:** Composed of rocky and/or metallic material. Asteroids are large, and meteoroids are smaller (diameter cutoff is 100 meters).
  • **Impact Craters:** Result from collisions with massive bodies such as asteroids and comets; a crater on a planet or moon caused by the impact of a meteorite or other object.
  • **Astronomical Units (AU):** A unit of measurement equal to 149.6 million kilometers, the mean distance from the center of the Earth to the center of the Sun.
  • **Terrestrial Planets:** Terrestrial planets (like Earth) are inner planets and are smaller. Jovian planets (like Jupiter) are outer planets and are known as gas giants. All planets have a crust, mantle, and core.

Measuring Distances in Space

  • **HR Diagram:** A plot of stars according to their absolute magnitudes and spectral types. They show a relationship among the size, colors, and temperatures of stars.
  • **Light-Year:** A unit of astronomical distance equivalent to the distance that light travels in one year, which is 9.4607 × 1012 km (nearly 6 trillion miles).

Stars and Galaxies

  • **Stellar Evolution:** The process by which a star changes over the course of time.
  • **Apparent Magnitude:** The magnitude of a celestial object as it is measured from the Earth.
  • **Galaxies:** Consist of 1 billion to over 100 billion stars. Most are relatively flat. Stars in the galaxy don’t collapse from gravity because they revolve around a central area. Most galaxies probably have a black hole in the center, which accounts for a substantial part of its mass.
  • **Absolute Magnitude:** The magnitude (brightness) of a celestial object as it would be seen at a standard distance of 10 parsecs.

Cosmology

  • **Big Bang Theory:** Describes the birth, evolution, and fate of the universe. The universe was originally in an extremely hot, super-massive state that expanded rapidly in all directions.
  • **Red Shift:** A pattern where all galaxies appear to be moving away from the Milky Way because of the expansion of the universe.
  • **Cosmology:** The science of the origin and development of the universe.
  • **Doppler Effect:** Can be used to determine distances to very distant stars and galaxies by measuring the shift of hydrogen spectral peaks to longer wavelengths.
  • **Hubble’s Law:** Galaxies recede at speeds proportional to their distance from the observer.
  • **Stellar Parallax:** A method to measure the distance to stars. Distance is determined by the parallax angle; the smaller the parallax angle, the greater the distance to the star.