WEATHERCLIMATE  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. (-130 o 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 energy 3. 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?