Chapter Overview
This chapter introduces the Earth system, the composition of the atmosphere, weather and climate, atmospheric observations, and the major layers of the atmosphere.
Test 1
Chapters 1 and 2
Test date: See the Fall 2026 course schedule
Read both textbook chapters along with the online class notes.
Chapter 1 Video
The Earth System
Geosphere
The solid portion of Earth. Its scientific study is geology.
The solid portion of Earth. Its scientific study is geology.
Hydrosphere
All water on Earth. About 97% is found in the oceans. Its study includes oceanography.
All water on Earth. About 97% is found in the oceans. Its study includes oceanography.
Atmosphere
The envelope of air surrounding Earth. Its scientific study is meteorology.
The envelope of air surrounding Earth. Its scientific study is meteorology.
Biosphere
All life forms on Earth. Its scientific study is biology.
All life forms on Earth. Its scientific study is biology.
A system is a group of interacting parts that form a complex whole. In a closed system, energy may move in and out while matter does not. In an open system, both energy and matter can move into and out of the system.
Energy from the Sun
Solar energy drives external processes in the atmosphere, hydrosphere and at Earthās surface.
Energy from Earthās Interior
Internal heat powers processes that produce volcanoes, earthquakes and mountains.
The Hydrologic Cycle
The hydrologic cycle is one of Earthās many subsystems. Water continuously moves from the oceans to the atmosphere by evaporation, from the atmosphere to land by condensation and precipitation, and from land back to the sea through streamflow and groundwater.
Composition of the Atmosphere
- Nitrogen (Nā): about 78%
- Oxygen (Oā): about 21%
- Together, nitrogen and oxygen make up about 99% of the atmosphere.
- Other components include carbon dioxide, water vapor, ozone and aerosols.
- Water vapor can reach about 4% by volume and helps transport latent heat.
Aerosols
Tiny solid and liquid particles that can act as surfaces for condensation and can absorb or reflect solar radiation.
Tiny solid and liquid particles that can act as surfaces for condensation and can absorb or reflect solar radiation.
Ozone (Oā)
A gas concentrated mainly in the stratosphere that absorbs potentially harmful ultraviolet radiation from the Sun.
A gas concentrated mainly in the stratosphere that absorbs potentially harmful ultraviolet radiation from the Sun.
Weather and Climate
Weather
The day-to-day state of the atmosphere at a particular time and place. It concerns short-term changes.
The day-to-day state of the atmosphere at a particular time and place. It concerns short-term changes.
Climate
The long-term aggregate and statistical description of weather conditions for a place or region.
The long-term aggregate and statistical description of weather conditions for a place or region.
Important Weather Elements
- Air temperature
- Humidity
- Type and amount of cloudiness
- Type and amount of precipitation
- Air pressure
- Wind speed and direction
Current Weather
Climate Almanac
| Location | Time | Weather | Temp. (Ā°F) |
Dewpt. (Ā°F) |
Hum. (%) |
Heat Index (Ā°F) |
Wind (mph) |
Wind Gust (mph) |
Cloud Bases (100s ft) |
Vsby. (SM) |
Pres. (in) |
|---|
Cloud codes: FEW = few, SCT = scattered, BKN = broken, OVC = overcast, VV = vertical visibility. Wind direction is shown with compass direction and speed. Stations with unavailable or stale observations display āNo Report.ā
Long Island Climate Resources
Monthly almanacs summarize daily climate data, averages, records, precipitation, snowfall, sunrise and sunset times.
Observing the Atmosphere
Weather balloons carry radiosondes, lightweight instrument packages that transmit measurements of temperature, pressure and relative humidity. Airplanes, satellites, rockets and weather radar are also used to study the atmosphere.
Weather Balloon
Radiosonde
Layers of the Atmosphere
Using temperature as the basis, the atmosphere is divided into four major layers. The boundaries between them are called pauses.
Troposphere
The lowest layer and the āweather sphere.ā Temperature usually decreases with height.
Stratosphere
Contains the ozone layer. Temperature increases with height because ozone absorbs ultraviolet radiation.
Mesosphere
Temperature decreases with height. The mesopause is the coldest region of the atmosphere.
Thermosphere
Very thin air and temperatures that increase greatly with altitude. The ionosphere lies within this region.
NOAA Atmospheric Layers
Atmospheric Levels
Layer Structure
Lapse Rates and Stability
The average environmental lapse rate is about 6.5Ā°C per kilometer, or roughly 3.5Ā°F per 1,000 feet. It is not constant and must be measured regularly with radiosondes.
A temperature inversion occurs when temperature increases with height. In general, a larger temperature decrease with height indicates greater instability.
Absolutely Stable
Absolutely Unstable
Conditionally Unstable
The Ionosphere and Auroras
The ionosphere extends roughly from 80 to 400 kilometers above Earth and contains electrically charged particles. Its D, E and F regions affect radio signals and vary between day and night.
Auroras form when energetic particles from the Sun interact with atoms and molecules in Earthās upper atmosphere near the magnetic poles.
Aurora Borealis - October 10 2024 - Long Island
Red and Green Aurora
Aurora Australis
Test 1 Review
Test 1 covers Chapters 1 and 2. Be ready to explain:
- The major atmospheric layers and what makes each layer different
- Weather compared with climate
- Atmospheric gases, air temperature and pressure
- Why Earth has seasons and how sunlight angle changes
- Daylight changes on Long Island through the seasons
- The three methods of heat transfer
- Why sunsets appear red and the daytime sky appears blue
- Albedo and electromagnetic wavelengths