Meterology 225 exam 1

Key Meteorology Concepts and Definitions

Meteorology, Weather, and Climate

• Meteorology: The study of the atmosphere and weather patterns.

• Weather: The atmospheric conditions at a specific time and place.

• Climate: The long-term average of weather patterns over time.

Physical Characteristics of Weather and Climate

• Temperature

• Pressure

• Humidity

• Wind

• Precipitation

Natural Hazards Related to the Atmosphere

• Hurricanes

• Tornadoes

• Thunderstorms

• Droughts

The Four Spheres

• Atmosphere: The layer of gases surrounding Earth.

• Hydrosphere: All water on Earth (oceans, lakes, rivers, groundwater).

• Lithosphere: The Earth's solid crust and upper mantle.

• Biosphere: All living organisms and ecosystems.

Hydrosphere

• Includes oceans, lakes, rivers, glaciers, and groundwater.

• Covers about 71% of Earth's surface.

Human Influence on the Earth System

• Burning fossil fuels → Increased CO₂

• Deforestation → Reduced carbon absorption

• Pollution → Affects air and water quality

Energy Sources in the Earth System

1. The Sun (primary energy source)

2. Earth’s Interior (geothermal energy)

3. Gravitational Energy (tidal forces from the Moon and Sun)

Composition of the Atmosphere

• Main components:

  • Nitrogen (N₂) – 78%

  • Oxygen (O₂) – 21%

  • Argon (Ar) – 0.93%

• Variable gases:

  • Carbon dioxide (CO₂) – ~0.04%, varies seasonally, increasing due to fossil fuels.

  • Water vapor – Important for weather and climate.

  • Aerosols – Tiny solid/liquid particles affecting weather.

  • Ozone (O₃) – Protects from UV radiation.

Vertical Structure of the Atmosphere

1. Troposphere (0-12 km) – Weather occurs here, temperature decreases with altitude.

2. Stratosphere (12-50 km) – Contains ozone layer, temperature increases with altitude.

3. Mesosphere (50-80 km) – Coldest layer, meteors burn up here.

4. Thermosphere (80+ km) – High temperatures, auroras occur here.

Divisions Between Layers:

• Tropopause (between troposphere & stratosphere)

• Stratopause (between stratosphere & mesosphere)

• Mesopause (between mesosphere & thermosphere)

Atmospheric Pressure

• At sea level:

  • 1013.25 mb (millibars)

  • 14.7 psi (pounds per square inch)

  • 1 atm (atmosphere unit)

• Pressure decreases with altitude because there are fewer air molecules.

Ozone and UV Radiation

• Ozone absorbs harmful UVB and UVC rays.

• UVA reaches Earth's surface and can cause skin damage.

Environmental Lapse Rate

• The rate at which temperature decreases with altitude in the troposphere (~6.5°C/km).

Anvil Cloud Formation

• Forms at the top of strong thunderstorms when rising air reaches a stable layer and spreads out.

Altitudes of Atmospheric Layers

• Troposphere: 0-12 km

• Stratosphere: 12-50 km

• Mesosphere: 50-80 km

• Thermosphere: 80+ km

Cause of Seasons

• Earth's axial tilt (23.5°) relative to its orbit around the Sun.

Perihelion & Aphelion

• Perihelion: Closest to the Sun (~January 3).

• Aphelion: Farthest from the Sun (~July 4).

Tropics and Circles

• Tropic of Cancer: 23.5° N

• Tropic of Capricorn: 23.5° S

• Arctic Circle: 66.5° N

• Antarctic Circle: 66.5° S

UV Index

• Developed in the 1990s.

• Ranges from 0-11+.

• Higher values indicate higher risk of sunburn.

Electromagnetic Spectrum (from longest to shortest wavelength)

1. Radio waves

2. Microwaves

3. Infrared

4. Visible light

5. Ultraviolet (UV)

6. X-rays

7. Gamma rays

Energy and Wavelength

• Shorter wavelengths → Higher energy.

• Longer wavelengths → Lower energy.

Nanometer (nm)

• A unit measuring wavelength (1 nm = 1 billionth of a meter).

Radiation Laws

1. All objects emit radiation.

2. Hotter objects emit more radiation.

3. Hotter objects emit shorter wavelengths.

4. Good absorbers of radiation are also good emitters.

Heat and Energy Units

• Joule (J) – SI unit of energy.

• Calorie (cal) – Energy to raise 1g of water by 1°C.

• Watt (W) – Power unit (energy per second).

Heat Transfer Mechanisms

• Conduction: Heat transfer through direct contact.

• Convection: Heat transfer by fluid motion.

• Radiation: Heat transfer via electromagnetic waves.

Transmission, Absorption, Reflection, and Scattering

• Transmission: Energy passes through a medium.

• Absorption: Energy is taken in by a substance.

• Reflection: Energy bounces off a surface.

• Scattering: Energy disperses in multiple directions.

Albedo (Reflectivity of a Surface)

• Snow/Ice: High albedo (~80-90%).

• Forests: Low albedo (~10-20%).

• Earth’s average: ~30%.

Why the Sky Appears Blue

• Rayleigh scattering: Short-wavelength (blue) light is scattered more than other colors.

Why the Sun Appears Different Colors

• White/Yellow: Normal sunlight due to a mix of all colors.

• Red/Orange: During sunrise/sunset, light passes through more atmosphere, scattering away blue/green.

Temperature and Common Scales

• Fahrenheit (°F)

• Celsius (°C)

• Kelvin (K) (absolute scale, no negative values)

Temperature Terms

• Daily Mean Temperature: Average of daily max & min.

• Daily Temperature Range: Difference between daily max & min.

• Monthly Mean Temperature: Average daily means for a month.

• Annual Mean Temperature: Average monthly means for a year.

• Annual Temperature Range: Difference between warmest and coldest monthly mean.

Isotherm & Temperature Gradient

• Isotherm: A line connecting points of equal temperature.

• Temperature Gradient: Rate of temperature change over a distance.

Meteogram

• A graphical representation of weather variables over time.

Specific Heat

• The amount of heat needed to change a substance’s temperature.