psu meteo 201 exam 1

meteogram

- time display of weather information at a single location
- includes temperature, dew point, sea level pressure, wind, visibility, obstructions, and cloud cover

isopleths

lines of equal value

gradient

ΔΒ divided by distance

7 fundamental weather variables

temperature, air pressure, wind speed/direction, humidity, cloud cover, precipitation,

atmospheric moisture

humidity

bergeron-findeison process

- ice crystal process
- rain drop is large compared to cloud drop
- most raindrops outside of tropics begin as a snowflake then melt on their way down

wet bulb temperature

- parcel of air is cooled to saturation
- has to do with humidity

dew point

the temperature where water vapor starts to condense

virtual temperature

the temperature that a parcel of
dry air would have if it were at the same pressure and had
the same density as moist air

celsius to fahrenheit

9/5(temp)+32

fahrenheit to celsius

5/9(temp)-32

celsius to kelvin

temp+273.15

ideal gas law

P=ρVT

note: only for dry air

west coast seasons

summer: cooler
winter: warmer

- less seasonality due to wind from the ocean

east coast seasons

summer: warmer
winter: colder

- more seasonality
- landlocked

pressure =

force/area

pressure

weight of air column per unit area (~14.7 lb/in^2 at sea level)

pressure tendency

the amount of atomospheric pressure change in a given time period (typically 3 hours)

wind vector

u = horizontal component
v = vertical component

wind roses

use all 16 standard compass directions

absorption

object heats and/or changes phases

transmission

radiation passes through object

back scatter (reflect)

radiation emerges back towards the source

conduction

- molecular collisions transfer energy
- works greatest near the ground

convection

- parcels of rising air transfer energy
- "hot air rises"

greenhouse effect

- earths surface emits infrared energy to space
- CO2 and water vapor absorb some radiation
- naturally warms earth

low clouds

form below 6500 ft

middle clouds

form 6500-20000 feet (prefix: alto-)

high clouds

form >20000 feet (prefix: cirro-)

stratiform

- layered clouds
- sheets of clouds
- typically lower

cumuliform

- heaping clouds
- vertical extent is similar to horizontal extent
- driven by convection
- backscatters most visible radiation

cirriform

- thin, relatively transparent clouds
- made mostly of ice
- transmits most visible radiation

climatology

create a forecast based on average measurements

persistence

"what happened yesterday will happen today"

NWP

- numerical weather prediction
- grid point model
- spectral model

ensemble forecasting

- plume diagram
- spaghetti plot
- multiple companies/countries/people input their opinion to get a forecast

MOS

- a statistical forecasting technique that takes output from NWP models and transforms it into local forecasts
- uses a set of equations
- extremely good and sophisticated
- hard to beat

in-situ

instrument in direct contact with the medium

remote

instrument not in direct contact with medium

upper air observing network (radiosonde)

- temperature, relative humidity, pressure, wind
- balloon launch with instruments attached to measure the above