UNIT 2.1-4 notes EVR1001

Composition of the Atmosphere

~78% Nitrogen, ~21% Oxygen, ~1% trace gases (argon, CO₂, etc.), plus water vapor & aerosols.

Difference in Atmospheres

Photosynthetic microbes turned CO₂ into O₂ billions of years ago → oxygen-rich atmosphere vs. CO₂-dominant atmospheres on Venus/Mars.

Atmospheric Pressure

The force air exerts on a surface due to gravity pulling it toward Earth.

Measurement of Atmospheric Pressure

With a barometer (mercury rises/falls with pressure changes).

Standard Atmospheric Pressure Values

1 atm = 1,013 mb = 760 mmHg (29.92 in Hg).

Oxygen Tanks for Everest Climbers

Air pressure decreases with altitude → less oxygen available to breathe.

Layers of the Atmosphere

Troposphere → Stratosphere → Mesosphere → Thermosphere → Exosphere.

Weather Occurrence Layer

Troposphere (contains 75-80% of atmospheric mass).

Ozone Layer Location and Function

Stratosphere → ozone absorbs UV radiation, protecting life.

Coldest Layer and Meteor Activity

Mesosphere (~ -90°C).

Auroras Location

Thermosphere.

Layer Fading into Space

Exosphere.

Ozone Layer Damage and Treaty

CFCs and other manmade gases → Montreal Protocol phased them out.

Effects of Ozone Depletion

Increased skin cancer, cataracts, plant damage, reduced plankton populations.

Weather Definition

Short-term (hours/days): temp, wind, precipitation.

Climate Definition

Long-term (30+ years): averages of temp & precipitation.

Florida Seasons

2 seasons → Wet (May-Sept) & Dry (Oct-Apr).

Air Mass Definition

Large body of air with uniform temp/moisture.

Cold Front Process

Cold, dense air pushes warm air upward → warm air cools/condenses → precipitation.

Convection Cells

3 main convection cells: Hadley Cell (tropics), Ferrell Cell (mid-latitudes), Polar Cell.

Hadley Cell Description

Hot air rises at equator, moves poleward.

Ferrell Cell Description

Moves poleward/east at surface, equatorward/west at higher levels.

Polar Cell Description

Air sinks at poles → moves toward equator.

Prevailing Winds

Polar easterlies (poles → equator), Westerlies (mid-latitudes), Trade winds (tropics).

High Pressure Weather

High pressure (30° N/S & poles) → fair, dry weather.

Low Pressure Weather

Low pressure (50-60° N/S) → cloudy, wet weather.

Coriolis Effect

Rotation of Earth bends winds → right/clockwise (N. Hemisphere), left/counterclockwise (S. Hemisphere). Strongest at poles, none at equator.

Weather Measurement Tools

Thermometer - temp, Barometer - pressure, Anemometer - wind speed/direction, Hygrometer/Psychrometer - humidity & dew point.

North/Central Florida Climate

Humid subtropical.

South Florida Climate

Tropical.

Florida Summer Weather

Daily thunderstorms (sea/lake breezes + Atlantic subtropical ridge).

Florida Late Summer Weather

Tropical storms/cyclones.

Climate Change in Florida

+1°F warming in century, rising sea level (1 in/decade), stronger storms, reef damage, hotter days, less freezing risk for crops.

Weather

Short-term atmospheric conditions.

Climate

Long-term atmospheric patterns.

Cold Front

A weather front where cold air pushes warm air up, leading to cooling, condensation, and precipitation.

Prevailing Westerlies

Winds in the mid-latitudes that blow from west to east, resulting from convection in the Ferrell cells.

Trade Winds

Winds in the tropics that blow from east to west toward the equator, carrying heat and moisture poleward.

Florida's Seasons

Florida has wet and dry periods rather than four temperate seasons due to its proximity to the tropics.

Wet Season in Florida

May to September, characterized by daily thunderstorms and hurricanes.

Dry Season in Florida

October to April, marked by less precipitation.

Meteorological Disturbance

A change in atmospheric/weather patterns caused by shifts in temperature, pressure, humidity, wind, clouds, or precipitation.

Weather Phenomena Categories

1. Precipitation (rain, hail, snow, drizzle). 2. Obscurations (fog, smoke, dust, haze, volcanic ash). 3. Other wind-related (tornadoes, squalls, dust storms, waterspouts).

Hurricane Formation

Requires warm ocean water (>80°F) to fuel evaporation and cloud formation.

Coriolis Effect and Hurricanes

Hurricanes do not form near the equator due to the absence of the Coriolis Effect.

Origin of U.S. East Coast Hurricanes

Many originate as tropical thunderstorms off the west coast of Africa.

Hurricane Categorization

Categorized by the Saffir-Simpson Hurricane Wind Scale based on wind speeds.

Greenhouse Effect

Caused by greenhouse gases (CO₂, water vapor, methane, nitrous oxide) trapping infrared radiation, keeping Earth warm.

Enhanced Greenhouse Effect

Occurs when human activities increase greenhouse gases, leading to climate change.

Natural Climate Change Factors

Volcanic activity, solar changes, tectonic shifts, glacial and interglacial cycles.

Climate Stability Before Industrialization

Climate was stable for the past 10,000 years, supporting agriculture; sharp rise in temperature in the last 100 years due to human activity.

CO₂ Levels Since Industrialization

Pre-industrial levels were ~278 ppm; today (2016) levels are 400+ ppm, the highest in 800,000 to 15 million years.

IPCC

Intergovernmental Panel on Climate Change, which concluded with 99% certainty that humans cause modern climate change.

Predicted Changes by 2100

+2-4°C rise in temperature, sea level rise of 1-2 meters (3-6 feet).

Environmental Impacts of Climate Change

Melting glaciers/ice, sea level rise, stronger storms, droughts, desertification, biodiversity loss.

Human Impacts of Climate Change

Flooding of cities, aquifer contamination, food shortages, heat-related illness, spread of disease, economic damage ($5-90 trillion).

Example of Biodiversity Loss

Polar bears endangered (2008), coral bleaching, extinction of Hawaiian honeycreepers.

Air Pollution

Harmful gases, liquids, or solids entering the air from natural and human sources.

Air Quality Index (AQI)

Measures 5 main pollutants, set by the EPA under the Clean Air Act.

Major Pollutants Tracked by AQI

1. Particulate Matter (PM10 & PM2.5) 2. Nitrogen Dioxide (NO₂) 3. Ozone (O₃) 4. Sulfur Dioxide (SO₂) 5. Carbon Monoxide (CO).

Pollutant Creating Acid Rain

Sulfur Dioxide (SO₂), which forms sulfuric acid in water droplets.