WEATHER CLIMATE

The state of the atmosphere at a given time and place Combination of

Earth’s motion and sun’s energy

Influences everyday activities

Observations of weather over many years Describes a place

or origin

Many changes over the Earth’s 4.6 billion year history

2.5 billion years ago oxygen began to accumulate

Nitrogen and Oxygen dominate the volume of gases composing dry air. (99%)

Air is NOT a specific gas – it’s a mixture of gases

Which gas would you say plays a significant role

in heating the atmosphere?

Why? Carbon Dioxide is an active absorber of energy given off by the Earth.

Water vapor, dust particles, and ozone also have significant effects on weather and climate.

Water Vapor Source of all clouds and precipitation Absorbs heat given off by Earth Absorbs solar energy

Dust Particles mixture of solid particles and liquid droplets found

in the air May stay suspended for long periods of time Ex: dust, dirt, soot, or smoke, pollen, ash

Ozone Very little in atmosphere and unevenly distributed Concentrated 10 and 50 km above Earth’s surface Crucial to life on Earth Absorbs potentially harmful UV radiation from the

sun

Is there a beginning and end???? There is no sharp boundary Thins the further away from Earth you get

until too few gas molecules can be detected.

Four Layers of atmosphere based on temperature Troposphere Stratosphere Mesosphere Thermosphere

Troposphere – Bottom layer All important weather phenomena occur heated from below Nearly all of the water vapor and dust

particles in the atmosphere are in the troposphere

Stratosphere – Ozone is concentrated here Heated very dry; air there contains little water vapor

Mesosphere – higher up in the mesosphere, the temperature

gets colder. The top of the mesosphere is the coldest part

of Earth's atmosphere. (-130o F) Scientists know less about the mesosphere

than about other layers. Weather balloons and jet planes cannot fly

high enough to reach the mesosphere. The orbits of satellites are above the

mesosphere Meteors or rock fragments burn up here

Thermosphere – Contains tiny fraction of atmosphere’s mass. what we normally think of as outer space circulation in the thermosphere are largely

driven by these tides and waves Auoras (the Southern and Northern Lights) Orbit of space shuttle

Nearly all energy driving weather and climate come from the sun.

Solar energy is not distributed evenly over the Earth’s surface

Unequal heating creates winds and drives ocean currents. (weather)

Why is it colder in winter and warmer in summer?

Earth’s position relative to the sun Length of day Gradual change in noon sun’s angle above the

horizon Affects the amount of energy Earth recieves

23.5 degree tilt Always points

toward north star Position of Earth’s

axis to the sun is ever changing

No tilt = no seasons

Heat – energy transferred from one object to another because of differences in their temperature.

Temperature – measure of the average kinetic energy of the individual atoms or molecules in a substance

Three mechanism of energy transfer as heat:

Conduction, convection, radiation

Conduction – transfer of heat through matter by molecular activity Heat moves from higher temp. to lower temp.

Pot on stove

Metals are good conductors Air is a poor conductor

Convection – transfer of heat by mass movement or circulation within a substance Takes place in fluids, air, and solids

Energy carried from hotter regions below to cooler regions above by bulk buoyant motions of the gas.

Radiation – travels in all directions and has the ability to travel through a vacuum of space. Solar energy reaches Earth by radiation

So what happens to solar radiation when it hits the Earth????

1. Some energy is absorbed and converted to heat (water vapor and carbon dioxide/

Greenhouse effect)

2. Transparent substances transmit radiant energy3. Some radiation bounces off objects without being absorbed.

Reflection Bouncing off Reflected radiation

has same intensity as incident radiation

Scattering Disperses light in

different directions Large number of

weaker rays

How does weather differ from climate? In which direction does Earth’s axis point? Why do seasonal changes occur? What are the three mechanisms of energy transfer? What is convection? What causes blue color of the daytime sky? How are heat and temperature related? Contrast reflection and scattering. Describe what happens to solar radiation when it hits

the earth. How does water vapor affect energy transfer on earth? What are the three main components of the

atmosphere?

Temperature – one of the basic elements of weather and climate.

Temperature control – any factor that causes temperature to vary from place to place and from time to time.

Angle of sun’s rays and length of daylight depends on latitude (Seasons)

Other influential factors: Heating of land, water, altitude, geography,

cloud cover, ocean currents.

Which heats faster….land or water??? Land

Which cools faster …. land or water??? Land

Heating of Earth’s surface controls the temp above it. Different surfaces absorb varying amounts of solar energy.

Land heats more rapidly than water most land surfaces are darker than water

which means more absorption of solar radiation and heat.

land surface retains more heat. Thus, land surfaces warm more quickly than water

Dirt is a good insulator

Water reflects most solar radiation back to the atmosphere. absorbs heat readily not a good insulator

Temperature variations are greater over land than over water Geographic position, altitude, cloud cover and

albedo

Albedo – fraction of total radiation that is reflected by any surface.

Many _____ have a high albedo, and therefore reflect a significant portion of the sunlight that strikes them back to space.

Daytime More clouds in day yields lower temperatures

Night time Clouds act as a blanket yielding warmer

temperatures than on a clear night.

What is temperature control? What are 5 factors influencing

temperature? Which heats faster land or water? Why? What reflects more solar radiation; land

or water? Why? What is albedo? How does it affect

weather? How do clouds affect day and night time

temperature?