Weather and Hydrology Overview

Weather and Hydrology

• Hydrology and meteorology are integrated fields of study.
• Weather is the atmospheric state at a specific time and location, typically described by temperature, air pressure, humidity, wind speed/direction, precipitation, and cloudiness.
• Weather is the short-term condition of the atmosphere.
• Meteorologists study weather.
• Climate is a set of typical weather conditions for a given area, including the frequency of these conditions and their seasonal variations.
• Climate is determined over a longer period, usually 30 years.
• Climate describes the average weather conditions and statistical distribution.

Earth's Climate System

• Earth's climate system is comprised of multiple spheres.
• Lithosphere: solid earth (crust, upper mantle)
• Hydrosphere: all water (oceans, lakes, rivers, groundwater, etc.)
• Atmosphere: gases surrounding the earth
• Biosphere: all living organisms on earth

Components of the Earth's Spheres

• Lithosphere: Composed of rocky material, including loose soil and rocks, dense silicate rocks (partially molten rocks), liquid, molten rocks. Inner and outer core composed primarily of iron and nickel.
• Hydrosphere: The total amount of water on Earth in liquid, solid (ice), and gaseous (water vapor) form. Includes water on the surface, underground, and in the atmosphere. Significant amounts are freshwater and saltwater.
• Atmosphere: A gaseous envelope surrounding the Earth, held in place by gravity. It is composed primarily of nitrogen, oxygen, and argon, with smaller amounts of variable components like water vapor, carbon dioxide, methane, and ozone.
• Biosphere: The part of the Earth that supports life, including all living organisms (plants, animals, and microorganisms), water, rock, soil and the atmosphere. Energy is sourced from the Sun and the Earth's interior, and materials are recycled.

Atmosphere

• The atmosphere is a gaseous blanket of Earth where important gases circulate.
• The atmosphere surrounds the earth and is held by gravitational force.
• The atmosphere is comprised of clean dry air, water vapor, gases and impurities.
• Atmosphere is divided into layers (troposphere, stratosphere, mesosphere, thermosphere, exosphere).
• Each layer of atmosphere has differing altitudes, temperatures, and densities.

Layers of the Atmosphere

• Troposphere: 0-10 km altitude
• Stratosphere: 10-45 km altitude
• Mesosphere: 45-80 km altitude
• Thermosphere: 80-300 km altitude
• Exosphere: above 300 km altitude

Atmospheric Gases

• Constant Components: Gases that proportionately remain the same over time and location. Examples include Nitrogen (78.08%), Oxygen (20.95%), and Argon (0.93%).
• Variable Components: Gases that vary in quantity over a certain time or location. Examples include Water Vapor (0-4%), Carbon Dioxide (0.039%), Methane (trace amounts), Ozone (trace amounts), and other gases.

Roles of the Atmosphere

• Affects Earth's energy balance
• Supports the hydrological, carbon, and nitrogen cycles
• Provides conducive climate conditions for food and energy demands.

Greenhouse Effect

• The natural warming of the Earth, where gases in the atmosphere trap heat, preventing it from escaping into space.
• Greenhouse gases absorb and re-emit infrared radiation, keeping the Earth's temperature suitable for life.
• Human activities have increased the concentration of greenhouse gases, leading to the enhanced greenhouse effect and global warming.

Water Vapor

• Most abundant greenhouse gas in the atmosphere
• A major contributor to the greenhouse effect (approximately 60%).
• Warms the atmosphere due to increases in evaporation.
• Acts as a feedback mechanism to the climate system.
• Water vapor is removed from the atmosphere as precipitation and condensation.

Causes of Climate Change

• Orbital changes (Milankovitch cycles): Changes in Earth's tilt, orbit, and wobble affect the amount of solar radiation received.
• Variations in solar activity: Changes in the Sun's energy output can influence Earth's temperature.
• Volcanic eruptions: Volcanic emissions can temporarily cool the planet by blocking sunlight.
• Movement of plates: Movement of landmasses across the globe affects wind and ocean currents, and thus climate.
• Internal climate variability: Natural fluctuations within the climate system, such as El Niño-Southern Oscillation (ENSO).
• Greenhouse gases: Increased greenhouse gases trap more heat, causing the planet to warm.
• Extraterrestrial impacts: Large impacts from asteroids and comets can briefly cool the planet.

Factors Affecting Climate

• Extraterrestrial factors (e.g., solar output, Earth-Sun geometry, interstellar dust)
• Earth's systems (e.g., volcanic emissions, mountain building, continental drift)
• Atmospheric conditions (e.g., atmospheric chemistry, atmospheric reflectivity)
• Surface factors (e.g., ocean-atmosphere heat exchange, reflectivity of land surfaces).

Solar Constant

• The rate at which solar radiation is received per unit area at the top of the atmosphere, perpendicular to the sun beams.
• The average solar constant is 1368 W/m2 at an average distance from the Sun.
• Actual values vary by approximately ±3.5% between January (perihelion) and July (aphelion).

Orbital Configuration (Milankovitch Cycles)

• Milankovitch Theory: Links climate variations to changing parameters in Earth's orbit around the sun.
• Orbital configuration (eccentricity, obliquity, precession) affect the amount of solar radiation received by Earth in various ways.

Eccentricity

• Earth's orbit changes from elliptical to circular over a roughly 100,000-year period.
• Larger value of eccentricity leads to smaller variations in annual incident radiation.

Obliquity

• Refers to the tilt of Earth's axis, which varies between 21.5° and 24.5° over a period of approximately 40,000 years.
• The tilt of the axis causes variations in the intensity and duration of sunlight at different latitudes and across seasons.

Orbital Precession

• Earth's axis wobbles like a spinning top over a roughly 23,000-year period.
• This wobble alters the timing of equinoxes and affects the distribution of insolation (incoming solar radiation).

This quiz covers the integration of hydrology and meteorology, focusing on short-term weather conditions versus long-term climate patterns. Learn about the components of Earth's climate system, including the lithosphere, hydrosphere, atmosphere, and biosphere. Test your knowledge on these essential topics related to Earth's environment.