Weather and Meteorology Pt1

Weather and Meteorology

  • weather source: solar radiation, sun=source, heat energy stored in the planet (the oceans) and the atmosphere, not geothermal

  • Weather: state of the atmosphere in a particular place and time, everywhere, can be made worse by climate change

  • Climate: average weather fo a particular place over a long period of time

  • Hiyan Philippines 2013

    • 1 of most powerful category 5 hurricaes

    • 8000 dead

    • underestimated wave sizes, coastal towns=swept away

    • overpopulation, poor buildings, poor planning mass graves to avoid disease

  • Heat and the cold

    • kill the most people, elderly and the young, silent killers

    • European Heatwave 2003

      • 72,000 dead

    • Eurasia Heat wave 2010

      • 57,000 dead

  • What dives weather?

    • principle mechanism: the sun

    • the sun warms the oceans, they evaporate into the atmosphere

    • sun—>ocean—>atmosphere—>rotation of the Earth—>uneven solar atmosphere

    • tropical oceans get more solar absorption than polar

The Hydrologic Cycle

  • evaporation from ocean

  • condensation into ocean

  • evaporation from ocean rises up into atmosphere

  • condenses over land

  • precipitation onto land

  • surface + groundwater flow back to the ocean

  • Oceans= key high heat capacity, can store and expunge very high heat/kinetic energy

  • oceans moderate the climate

  • hurricanes-way for oceans to cool off

  • Evaporation: liquid to gas, heat energy absorbed

  • Condensation:

    • gas to liquid

    • gas cools

    • creates clouds

    • heat energy released into the atmosphere, powers weather

Characteristics of the Atmosphere

  1. Solar radiation

    • absorbed by oceans at tropics and sub-tropics

    • stronger at the equator

    • bc comes at a straight angle, 90 degrees, strikes most directly, heat surplus

    • direct flashlight illumination

  2. Temperature

    • temperature decreases with altitude

    • troposphere: where all weather occurs

      • above the lithosphere

      • overturn=where convection occurs, warm air rises, cold air sinks

      • 1st 12km of atmosphere

      • planes fly in tropopause to avoid weather and turbulence

  3. Density

    • warm air, less dense, rises

    • cold air, denser, sinks

  4. Water vapor

    • warm air, humid=least dense, less dense so rises, very buyout

    • cold air, dry, denser, sinks

  5. Pressure

    • weight that the air exerts over a surface

    • low pressure L

      • light column of air, air rising, not a lot of molecules, rainfall

    • High pressure H

      • heavy column of air, air sinking, lots of molecules, fair weather sunshine

    • Wind pressure: movement of air from high to low pressure

    • at equator lots of evaporation, low pressure

    • 30 degrees subtropics, typically high pressure systems, dry warm sunshine

  • Convection Cells

    • equator; equatorial low

      • very warm humid air over oceans, less dense, rises, low pressure

      • warm humid rising air

      • Low pressure: expands and cools=expansional cooling

      • condensation—>clouds

        • weather: rain, instability

        • empties all the weather becomes dry

        • moves north and south to subtropics and starts sinking

      • 30 degrees North and south in troposphere=hottest weather

      • cold, ry air sinks

      • High pressure

        • compressed (lots of molecules smushed together), warms, higher kinetic energy=high heat

        • weather: hot ,dry

      • Sand Diego=32 degrees of latitude,

        • in california, don’t have bc cold current

        • On East coast don’t have bc warm currents

      • 30 degrees=great desserts

Coriolis Effect

  • Trade Winds: come from the East as air sinks in Hadley Cell at 30 degrees, creates winds from high pressure to low pressure= trade winds

  • Westerlies: come from the west, the majority in the US

  • nothing goes in a straight line except at the equator

  • In the Northern Hemisphere everything veers off to the right

  • In the Southern everything veers off to the left

  • Earth’s rotation moves objects

  • At the equator the Coriolis effect is minimum

  • Max effect at the Poles

  • Prevailing Winds

    • originate at the subtropical high 30 degrees of latitude, High pressure

    • Trades/Easterlies

      • equator-30 degrees

      • flow East to West towards the Equator

    • Westerlies

      • 30-60 degrees of latitude

      • flow south west to north east towards the poles

      • 30-60 degrees= tornadoes formed

      • 0-30 degrees= hurricanes formed

      • most people live between 30-60 degrees

Cyclones and Anticyclones

  • in the northern hemisphere

  • Cyclone:

    • air converges in a low pressure system, starts rising and rotating counter-clockwise as goes into troposphere then diverges aloft in troposphere

    • warm and humid air converges at a low and starts rising spinning counter-clockwise

    • as rises starts cooling triggering condensation clouds instability and rain

  • Anticyclone:

    • starts sinking towards surface, rotates clock-wise, diverges at the surface from high to low

    • converge at top cold and dry air starts sinking, starts spinning clockwise

    • as sinks compresses and heats up

  • San Diego=Anticyclone bc at 30 degrees latitude

  • Anticyclone in Mediterranean

Wild Fires: an application of high pressure systems

  • High pressure system: air falling to surface, heating up and diverging

  • Santa Ana winds= very strong High pressure systems that peak in October

    • very hot dry air coming from dessert goin through canyons to the ocean

    • moves from dessert to ocean because moves clockwise

  • Fire Causes

    • humans cause 84%

      • burning trash

      • downed power lines

      • equipment use/malfunction

      • cigarettes, campfires

      • fireworks

      • arson

    • last 3 decades most destructive in CA history

      • acreage burnt

      • structure lost

      • death tolls

    • 16% lightning

  • Why CA?

    • population in wild-lands

    • intrinsic fire hazards

    • latitude =30 degrees, dry hot

    • med climate

    • very wet winters—> destructive fire season

    • dry, hot condition, fast santa ana winds