Atmosphere - layer of gases that surrounds a planet or moon held by gravity

(ocean of air)

Composition• Atmosphere is a

Mixture of– Gases– Dust– Water vapor• clouds and

precipitation (rain)• Absorbs heat and

energy from the sun

• changes by time and place

Ozone (O3) – very rare and less stable type of oxygen molecule that combines 3 atoms

of oxygen• Thin layer is found in

the Stratosphere– 3 ozone for every

10,000,000 air molecules

• Protects living things from harmful UV sun rays

• Manmade chemicals destroy ozone. Humans have thinned the layer above the Antarctic

Carbon Dioxide (CO2) - naturally occurring gas in our atmosphere

• Needed for photosynthesis to occur during the Carbon Cycle

• (photosynthesis) -plants take in (CO2),

solar energy, and water and produce carbohydrate energy (sugars) and Oxygen

Water Vapor - water in the atmosphere

• Key to understanding atmosphere processes• Water vapor is the source of all precipitation• Examples– Clouds– Fog– Rain– Snow– Sleet– hail

Changing state of matter• changing matter

requires energy is transferred in the form of heat

• Latent heat – heat used doesn’t cause temperature change

How water changes states of matter in the atmosphere

• All water passes through the atmosphere as water vapor

• Water changes from one state of matter to anothero Solid to liquido Liquid to gaso Solid to gas

Greenhouse Effect – The warming of Earths surface and lower atmosphere when carbon dioxide, water vapor and

other gases absorb and reradiate (heat) energy

The atmosphere is divided into 4 main layers by temperature

• Troposphere (bottom layer)• Stratosphere (where important weather

occur)• Mesosphere• Thermosphere (top layer)• It generally gets colder as altitude increases• Layers of the atmosphere are divided by

temperature and height

Layers of the atmosphere

Weather – the state of the atmosphere at any given time and

place• Climate – average weather conditions in an

area over a long period of time

Earth-Sun relationship• Almost all energy that causes Earth’s weather

and climate comes from the sun• Unequal heating of Earth causes weather

Heat transfer

• Heat transfers in 3 ways

1. Conduction – transfer of heat through molecular activity (high to low temp)

2. Convection – transfer of heat by mass movement or circulation within something

3. Radiation – transfer of heat in all directions

Solar radiation – when radiation strikes an object, 3 things happen

1. Energy is absorbed by the object

2. Energy is transmitted and doesn’t add to the object

3. Energy is reflected or bounced off the object

• Reflection – when light bounces off an object

Scattering – when a large number of weaker rays are produced traveling in different direction

Other factors that influence energy coming into the atmosphere

• Earth’s rotation – spinning

• Earth’s revolution – orbit around sun

• Earth’s orientation – how Earth is tilted on it’s axis in relation to the sun

Humidity – the amount of water vapor in the air• Relative humidity – the

amount of water in the atmosphere. % of how much the air can hold

• Saturation – when the atmosphere has reached it’s maximum amount of water vapor it can hold at a temperature and pressure

Dew point

• The temperature when water vapor in the air condenses (changes) into a liquid from a gas

Cloud Formation

• As air rises in the atmosphere it expands and cools

• When air reaches it’s dew point, clouds begin to form

Air compression• When air

pressure increases, air temperature rises

• Motion of the gas molecules increases

• When air pressure decreases, air expands and temperature cools•Motion of the gas molecules slows

Orographic Lifting• when air is

forced to rise and cool due to terrain features such as hills or mountains

Frontal Wedging

• When cold dense air acts as a barrier and causes warmer, less dense air to rise

Convergence• When air masses

flow together from more than 1 direction, air rises.

Low pressure is the result

Localized convective heating

• Unequal heating of Earth’s surface causes pockets of air to be warmed more than surrounding air

• Causes pockets of air to rise, forming thermals

Clouds – 3 basic types are classified on form and height

Cirrus

Cumulus

Stratus

High Clouds

a) cirrusb) cirrostratus c) cirrocumulus• Thin and white• Low precipitation• May warn of

approaching stormy weather

cirrocumulus

Middle Clouds - alto

a) Altocumulus – large and dense

b) Altostratus – white or gray sheet covering sky

c) Cumulonimbus - • Infrequent light

snow or drizzlealtocumulus

Low clouds

a) Stratus – fog like layer covering sky

- Occasionally produce light precipitation

b) Stratocumulus – rainy clouds

c) Nimbostratus – main precipitation maker

d) Cumulus - clouds with vertical development

Stratocumulus

Fog – cloud with base at or near the ground

• Form by 1.Cooling – air

over a cold surface

2.Evaporation – when cool air moves over warm water (steaming)

How precipitation forms

• Tiny cloud droplets grow in volume by about 1,000,000 times.

Cold cloud precipitation• Ice crystals

contact with cloud droplets causing them to freeze

• Causes ice to grow into snowflakes

• Rain often begins as snow high in the clouds

Warm cloud precipitation

• Large droplets moving through the clouds collide and join (coalesce) with smaller droplets

The type of precipitation that reaches Earth’s surface depends on

temperature in the lower atmosphere

• Rain• Snow• Sleet• Glaze• Hail

1. Earth’s atmosphere is made up of a combination of gases. The major components of nitrogen, oxygen, and argon remain constant over time and space, while trace components like CO2 and water vapor vary considerably over both space and time.

2. The atmosphere is divided into the thermosphere, mesosphere, stratosphere and troposphere

3. boundaries between these layers are defined by changes in temperature and height

4. Pressure decreases exponentially with altitude in the atmosphere.

5. Our knowledge about the atmosphere has developed based on data from a variety of sources, including direct measurements from balloons and aircraft as well as remote measurements from satellites.

Atmosphere key ideas