MET1010 Chapter 5

Adiabatic Temperature change

Temperature change without the addition or subtraction of heat

Lifting air causes ? How?

Lifting air causes cooling by expansion ( produces clouds/precip)

-Pressure decreases, Temperature decreases, RH increases

Sinking air causes?How?

-Heating by compression (Produces good weather)

-Pressure increases, Temperature increases, RH decreases

Dry adiabatic lapse rate

Rate at which unsaturated air heats or cools (10 degrees celcius/kilometer)

Wet adiabatic Lapse rate

Rate by which saturated air cools or heats by (5 degrees Celsius/ kilometer)Ins

Atmospheric Instability

Lapse Rate > Dry adiabatic Lapse rate , known as ABSOLUTE UNSTABLE

Atmospheric Stability

Lapse Rate < Wet Adiabatic Lapse Rate, ABSOLUTELY STABLE

Conditional Instability happens when

The lapse rate is between the wet adiabatic lapse rate and dry adiabatic lapse rate, 5<LR<10

• If the air is saturated, it is conditionally unstable

• If the air is unsaturated, it is conditionally stable

Absolutely Unstable

• Lapse Rate is higher than the dry adiabatic lapse rate (10)

• When air is lifted in this environment it keeps rising

• It is warmer than the surroundings

  • Causes clouds and precip

Absolutely Stable

-Lapse rate is less than wet adiabatic lapse rate (5)

-When air is lifted in this environments it sinks back to its original position

-Colder than the surroundings

Stablity enhanced

Stability will happen if we either sink or cool or sink air

What are the three ways stability will happen?

1-Radiational cooling after sunset

2-Subsidence (sinking) in a column of air (pressure inc, temp inc, RH dec)

3-Moving warm air across a cooler surface

What are the four ways instability will happen?

1-Increased heating/radiation (convective thunderstorms ) (Pressure decreases, Temperature decreases, Relative Humidity increases) 2-Forceful lifting mechanism ( fronts : warm- unstable and bring heavy precip, cold ( stable and bring light rain/drizzle. 3-Moving of cold air across a warmer surface 4-Covergence of air

What are condensation nuclei? Name them

Surfaces that water vapor can condense on.

-Dust, Smoke, Pollen, Salt (Hygroscopic)De

Describe the Collision-caolescence process

Warm clouds

Oppositely charged droplets collide and join together, and this can only produce RAIN.

One rain drop equals

One million collisions

Bergeron Process

Cold Clouds-

Supercooled water droplets (liquid droplets with below freezing temp) freeze on contact, followed by ice crystals growing at the expense of the supercooled water droplets.

This can produce any kind of precip

Snow

-Most common in the winter

-Formed in the Bergeron Process

-Solid

Sleet

-Normally a winter type of precip

-Formed in the Bergeron process

-Solid Ice crystals melt, and then refreeze into ice pellets

Freezing rain

-Normally a winter type of precip

-Formed in the bergeron process

-Ice crystals melt and then become supercooled , freeze on contact

Hail

-Most common in the spring

-Formed in bergeron process

-Solid

-Cumulonimbus clouds

-Ice crystals grow as swept and mixed with supercooled droplets

Standard Rain Gauge

-Accurate to .01'“

-Can total 11”rain

-1'“liquid=10” snow