This PowerPoint contains information on: Temperature Variation on Earth Water Vapor – Relative Humidity – Dew Point

Temperature Variation on Earth Goal: Explain our atmosphere’s interaction with the Sun’s radiation

Review: What happens to Solar Radiation? 50%- absorbed by land & sea 20%- absorbed by atmosphere and clouds 30%- lost to space by reflection and scattering reflection =20% from clouds = 5% from surface scattered =5% from atmosphere

Solar radiation is not distributed equally on Earth.

Latitudinal Temperature Differences Unequal distribution results in latitudinal temperature differences. LINES OF LATITUDE

Unequal Distribution of Heat from the Sun Equator-The sun's rays strike Earth most directly near the equator = more energy Poles- Near the poles, that same amount of solar energy is spread over a much larger area= less energy

Mapping Thermal Energy in the Atmosphere Isotherms are lines on a weather map that connect points where the temperature is the same. Isotherms generally trend east and west and show a decrease in temperatures as latitude changes from the tropics toward the poles.

What other factors influence temperature differences on Earth?  There are four main factors that cause differences in temperature on Earth: 1. Altitude 2.Heating of land vs. water (Surface Characteristics) 3. Geographic Position 4. Cloud Cover

*Altitude is the distance measured above ground or sea As altitude increases in the troposphere temperature decreases. 1.Temperatures vary because of Altitude

Mean Monthly Temperatures for Guayaquil and Quito in Ecuador, South America Ex: Altitude Q: Based on temperatures in the graph to the right, which city is located at a higher altitude?

2.Temperatures vary because of surface characteristics NOTE: Surface temperatures control air temperatures! Land Surface vs. Water Surface -Land and water absorb the sun’s radiation differently -Water has the ability to absorb and store more radiation then land HOWEVER, land heats more rapidly and to higher temperatures than water. Land also cools more rapidly and to lower temperatures than water.

Land vs. Water- Vancouver and Winnipeg Look at the graph below of Vancouver, British Columbia and Winnipeg, Manitoba. -Vancouver is located along the Pacific (marine) coast near water. -Winnipeg is surrounded by land and far from the influence of water -Both cities are close to the same line of latitude

Continued….. Land vs. Water - Similar latitude means that both cities will experience similar lengths of daylight and incoming radiation. HOWEVER: Winnipeg has much greater temperatures than Vancouver. Vancouver’s temperatures are controlled by the Pacific Ocean and Winnipeg’s are not!

3.Temperatures vary because of geographic position: FACT: In the Northern Hemisphere major winds move to the right

Ex 1: Coastal vs. Coastal Position (Leeward vs. Windward) Eureka, CA and New York City, NY Ex: GEOGRAPHIC POSITION

1)Coastal Positions A coastal location like Eureka, CA where prevailing winds blow from the ocean toward the shore (windward)will experience a significant difference in temperatures than a coastal location like New York City where the winds blow from the land toward the ocean (leeward).

Ex 2: Continental vs. Coastal Position Ex: GEOGRAPHIC Position

2) Coastal vs. Continental Position: Mountains can act as wind barriers and block wind from the ocean. Even though Spokane, WA is close to Seattle, WA the Cascade Mountain range separates both cities. Seattle is closer to the ocean and therefore will have more of a marine temperature influence. Spokane however is influenced by surrounding land surface temperatures instead of the ocean.

4. Temperatures vary because of cloud cover (albedo effect): Albedo is the fraction of total radiation that is reflected by any surface such as a cloud. Cloud Cover-Many clouds have a high albedo and therefore reflect back to space a significant portion of the sunlight that strikes them.

Temperatures vary because of how: Clouds Reflect and Absorb Radiation Reflect radiation from Sun Absorb radiation that was absorbed by land

COMING UP NEXT: WATER IN OUR ATMOSPHERE

Water in Our Atmosphere Goals Explain the importance of water vapor and its influence on: 1.relative humidity 2.dew point 3.precipitation

What is Water? One water molecule consists of two hydrogen atoms that are covalently bonded to one oxygen atom.  H 2 0 Water exists in three states of matter (S-L-G) State 1: Solid State = (Ice) State 2: Liquid State =(Fluid) State 3: Gas State = (Vapor)

What is Water Vapor? Water vapor is the gas state of H 2 O It is the most important gas in the atmosphere for understanding atmospheric processes

How Does Water Vapor Form? H 2 O can change from one state to another through a process called: phase change Important Note: The process of changing states requires a transfer of thermal energy (heat)

Phase Changes as Energy Increases Phase Change 1: melting= Solid to Liquid Ex: Ice melting in a cup Phase Change 2: evaporation =Liquid to Gas – As thermal energy is absorbed by water, the molecules begin to move quickly enough to escape the surface of the liquid and become gas Phase Change 3: sublimation= Solid to Gas – Solids are quickly converted to gas without passing through the liquid state (Ex: = dry ice)

Phase Changes as Energy Decreases Phase Change 4: Condensation= Gas to Liquid Ex: Mirror fogging up during shower Phase Change 5: Freezing =Liquid to Solid Ex: Making Ice Cubes Phase Change 6: Deposition = Gas to Solid – Fast conversion from gas  solid without changing through the liquid state (Ex= frost on a car window)

Water Phase Change Diagram In order for a phase change to occur ENERGY MUST BE TRANSFERRED!!!!!!!!!!!!!!!!!!!! Heat Energy

Phase Change Chart Phase ChangeStates of WaterFinal State of WaterExample Solid to LiquidIce to FluidFluid Water (liquid)Ice melting in a cup Liquid to GasFluid to VaporWater Vapor (gas)A puddle evaporating in the sun SublimationSolid to VaporWater VaporDry Ice DepositionVapor to SolidIceFrost deposited on a window

Humidity Humidity is a term used to describe the amount of water vapor in the air – Ex: The air in the room has 97% humidity Saturation is a term used to describe how much water vapor a kilogram of air needs in order to be considered full – Ex: warm air can hold more water vapor than cold air

Relative Humidity Relative humidity is a term used to describe how much water vapor the air will hold a certain temperature – Ex: When it is 77F degrees outside then 20 grams of water vapor is needed in every kilogram of air for the air to be fully saturated – Ex: When it is 50F degrees outside then only 7 grams of water vapor is needed in every kilogram of air for the air to be fully saturated 7g of water vapor 20g of water vapor 1 kg of air

20g of vapor Relative Humidity If the amount of water vapor in the air does not change, then – 1) as temperature decreases relative humidity will increase – 2) as temperature increases relative humidity will decrease WARM AIR COLD AIR The cold air is now holding more water vapor per section of air than the warm air. Remember- the amount of water vapor is the same, but warm air can store more vapor than cold air 20g of vapor

Dew Point The dew point is the temperature at which the water vapor in the air condenses into liquid water. – High dew point = moist air – Low dew point = dry air

– THAT’S ALL FOLKS

Water’s Changes of State Water can change from one state to another through a process called: phase change Phase Change 1: Solid to Liquid Phase Change 2: Liquid to Gas Phase Change 3: Solid to Gas In order for a phase change to occur ENERGY MUST BE TRANSFERRED!!!!!!!!!!!!!!!!!!!!