Climate and Weather Analysis Midterm 2

Stratospheric Ozone

“Good Ozone”
- provides protection from UV light

Tropospheric Ozone

“Bad Ozone”
- Linked to respiratory illness

What are 3 ways we can measure ozone in the atmosphere?

a) Dobson Ozone Spectrophotometer
b) Ozonesonde
c) Satellite remote sensing

Phases of Water

Gas, Liquid, Solid

Evaporation

Liquid to Water Vapor

• requires heat

Condensation

Water Vapor to Liquid

• Latent heat of Vaporization or Condensation

• releases heat

Melting

Solid to Liquid

Freezing

Liquid to Solid

Sublimation

Ice to Water Vapor

Deposition

Water Vapor to Ice

Saturation

Equilibrium where rate of condensation is equal to the rate of evaporation

What does saturation depend on? Why?

• Temperature

• Warm air can hold more water molecule than cold air

Humidity

• The amount of water vapor in the air

• varies through space and time

What are the different ways humidity can be defined?

• Specific Humidity: Mass of water vapor/mass of air

• Mixing ration: mass of water vapor/mass of dry air

• Vapor pressure: the pressure exerted by water vapor molecules in an air parcel (Dalton’s Law of Partial Pressure.

How can RH be changes?

• Change vapor content

• change temperature and this saturdation

Dewpoint temperature

• temperature at which relative humidity will occur

• alway less than or equal to temperature

Specific Humidity

mass of vapor/mass of air

• depends on evaporation and temperature

Which is heavier moist air or dry air?

Moist air is lighter

• when warm, moist air mass meets cold, dense air mass, the warm air rises

How does relative humidity relate to human comfort?

High relative humidity = less evaporative cooling

• sweat cannot evaporate and cool the body

Atmospheric Rivers

• narrow regions responsible for the majority of poleward water vapor transport across the midlatitudes

• High water vapor content, strong low level winds

  • Causes extreme precipitation in mountain regions

Stability

air parcels that can expand and contract freely without mixing with the air around them

• no energy exchange with the atmosphere

Unstable

• The temperature of the air parcel is warmer than the temperature of the air

  • Rising and expanding

Stable

• temperature of the air parcel is lower than the temperature of the air

  • sinking and compressing

neutral

air parcel is the same temperature as the air around it

• no rising or sinking

Adiabatic Process

• no heat exchange with environment

  • reversible

What happens to an air parcel as it rises?

Rising air expands and cools adiabatically without exchanging heat

• pressure parcel > pressure air

• expands, so the temperature in the parcel decreases

What happens to an air parcel as it sinks?

• P parcel < P air

• Air shrinks and compresses the parcel

• So the temperature inside the parcel increases

Dry adiabatic lapse rate

• rate of temperature change of the air parcel with increasing altitude when the parcel in unsaturated

• temperature decreases ~10 degC/km (9.8 deg C/km)

Moist Adiabatic Lapse Rate

• When air parcel is saturated it condenses, and latent heat is released which leads to adiabatic cooling

• Once moist parcel cools at moist adiabatic lapse rate

• 4.5 degC/km

What are conditions for stability based on the lapse rate of an air parcel?

Absolutely unstable - ELR > DLR

Conditionally Unstable - DLR > ELR > MLR

Absolutely Stable - ELR < MLR

What are the processes that destabilize an air parcel?

1. Cooling the air aloft

   1. Warming at the surface

Inversions

As temperature cools at night, cold air sinks and pools, water vapor condenses creating fog

• skewT show high relative humidity at the surface

• Inversion above the surface (temperature warmer at higher levels than at the surface)

• Warmer air aloft acts like a lid, holding colder air near the ground