Weather Part 1

Weather

Weather

The Atmosphere

The cloud of gasses and suspended particles surrounding earthBecomes less dense as altitude increasesMade up of layersProtective bubble that gives UV protection, breathable air, and moisture78% N2, 21% O2, .9% Ar, and .033% CO2Water Vapor runs from almost 0% in deserts to nearly 4% in tropical rain forests

Layers of the Atmosphere

5 layersIdentified byThermal characteristicsCompositionAir movementDensity

Troposphere

Starts at earths surface and runs to between 4 and 12 miles thick depending on latitude11-12 miles thick at the equator and thins to 4 miles thick at the polesTemperature decreases as altitude increasesTransitional zone between layers is called a ______pause (tropopause)

Stratosphere

From the tropopause to 31 miles above earths surfaceHolds 19% of atmospheres gasesUV radiation is absorbed by O2 molecules making O3Causes temperature to go up as altitude increasesDivided by the stratopause

Mesosphere

From stratopause to 53 miles above earths surfaceLess dense than stratosphereAs altitude increases, temperature decreasesSlows down meteorites, leaving a trail in the night sky

Thermosphere

From mesopause to 430 miles above earths surfaceExposed to very high amounts of UV radiation and X-raysAs altitude increase, temperature increasesFeels cold because of very low densityContains ionosphere causes radio waves to reflect back to earthAlso causes aroras

Exosphere

From thermopause to 6200 miles above earthArea where satellites orbit

Air Pressure

Air has mass and therefore exerts pressure as it piles up above usAs the density of air increases, the pressure of the air increasesAs the temperature of air increases, the density of the air decreasesAir pressure is exerted in all directions at onceStandard air pressure at sea level is 14.7 lbs/in2

Pressure and Elevation

As elevation increases, air pressure decreases, because there is less atmosphere above you.Due to this variation, air pressure at two different locations cannot be compared.We use sea level as the basis for a standard conversion for each location.Measure air pressure in inches of mercury or millibars.Standard air pressure at sea level is 29.92 inches of mercury or 1013.2 millibars.

Pressure and weather

Pressure systems are labeled as high or lowHigh pressure is associated with clear skiesLow pressure is associated with cloudy skiesBecause cold air is more dense than warm air, the highest air pressure readings are found on cold, clear days.

The Transfer of Heat Energy

Heat energy is transferred through:RadiationConductionConvection

The Suns heat is what fuels our planets weather.

Radiation

Heat transferred through electromagnetic energy. (excited atoms)This is how the sun heats our planetDark objects absorb more radiation that light colored objects

Conduction

Transfers heat through two solid objects touchingMetal spoon on a hot surface gets hot

Convection

Heat is transferred through moving fluidsAir in the atmosphere acts as a fluidHot air masses rise causing mixing of the atmosphereAlso causes windsLand heats up by radiation which heats air by conduction, which heats atmosphere by convection

Earth-Atmosphere Energy Balance

We have incoming energy from the sun and outgoing energy reflected by earths surfaceThe air molecules trap some reflected heat, creating a warming blanket around earthThis stabilizes our temperatureCloud cover traps even more of the reflected heat closer to the earths surfaceCloudy nights cool off less that clear nights

The ocean absorbs, stores, and releases heat and moisture into our atmosphere driving much of our weather.The top 10 feet of ocean contains more heat that the entire atmosphere.

Layers of the Ocean

Epipelagic sunlight zone surface to 660 ftWind causes mixing and therefore even temp distAt end of layer is the thermocline rapid decrease in temp with relation to depthMesopelagic twilight zone 660 ft to 3,300 ftBathypelagic - midnight zone - 3,300 ft to 13,100 ftOnly light comes from bioluminescenceConstant temperature of 39o FAbyssopelagic 13,100 ft to 19,700 ftLittle to no life, pitch black, extreme pressureHadalpelagic 19,700 ft to 35,000+ fttrenches

Salinity

Ocean water is salty.Most of the salt is NaCl, but some is MgCl or KCl.Different areas of the earths oceans are saltier than others.Around the equator and the poles are the least salty because of high rain fall and ice melt.The Atlantic, Persian Gulf, and Red Sea are the most salty due to high evaporation.Salinity is measured in grams of salt per liter.Normal salt levels are around 35 g/l

Molecular Properties of Water

The density of water increases as temperature decreases up to about 40o F.Between 40o F and 32o F, the molecules begin locking together and decreasing the density.As a result, ice floats and expands.About 9% expansion by volume.However, salt decreases the temperature at which water freezes.Sea water freezes around 28o F

So why do salinity, density, and temperature matter?

The temperature and salinity of the water impacts is density.The density of ocean water directly impacts ocean circulation patterns.Ocean circulation patterns influence most of our weather patterns in one way or another.

Ocean Circulations

Surface currents along the west coasts flow toward the equator and bring cold water from the poles to the equator.California Current that keeps San Francisco cool.Surface currents along the east coasts flow toward the poles and bring warm water to the poles.Gulf Stream that keeps England warmer.The deep ocean currents that circulate the global oceans is called the great ocean conveyor.

The Great Ocean Conveyor

Themohaline Circulation Thermo (tempurature) & Haline (salt)

Water takes about 1000 years to complete

Sinking

Up welling

The sea breeze

Because the land heats up and cools off more quickly than the ocean, the difference in the air temperature over these bodies, also heats up/cools off correspondingly.Warm air masses rise above land pulling in cool ocean breezes during the day.Warm air masses over water rise and pull cool land breezes during the night.

Sea Breeze

Land Breeze