Midterm Flashcards
Random error analysis equation
Know
1st / 2nd order response
Think motion on a line vs oscillation
1st order is Mercury thermometer
2nd order is wind vane (because oscillation and damping)
NIST
National Institute of Standards and Technology
NWS
National Weather Service
NOAA
National Oceanic and Atmospheric Administration
BIPM
Bureau International des Poids et Mesures
SI
Systeme International
NEXRAD
Next Generation Radar
IRT
Infrared Thermometer
PRT
Platinum Resistance Thermometer
RTD
Resistance Temperature Device
GOES
Geostationary Operational Environmental Satellite
POES
Polar Operational Environmental Satellite
ARB
Air Resource Board (or CARB for California)
DWR
Department of Water Resources
CIMIS
California Irrigation Management Information System
Basic Electricity Equations:
- resistance in series
- resistance in parallel
- voltage divider
in series: add resistances
in parallel: R_total = (1) / [1/R_1 + 1/R_2 + … + 1/R_n ]
loop rule
Convert Celsius to Fahrenheit
T_F = (9/5)T_C + 32
Convert miles to kilometers
1 mile = 1.609 km
Convert pounds to kilograms
1 kg = 2.205 lbs
Kurtosis
In a distribution…
low kurtosis: small “tails” = few outliers
high kurtosis: large “tails” = lots of outliers
Skewness
negative skew = “skewed left” = long tail on the left
positive skew = “skewed right” = long tail on the right
primary standards, secondary standards, tertiary…
primary: taken as true value
secondary: calibrated against primary
tertiary: …
input
actual variable (i.e. atmospheric conditions) and standards (to calibrate instrument)
output
observable variable that can be “tranduced” measured then converted to the desired quantity, (i.e. length converted to temperature)
repeatability
instrument gives same value for same standards
resolution
smallest detectable change in variable
drift v. stability
stable: low drift from calibration over time
drift: speed in which instrument slips from calibration over time
hysteresis
whether previous recorded values affect future measurements (e.g. humidity sensor which retains moisture)
linearity
between input and output variables:
need only to measure and calibrate at 2 values to get relationship equation
threshold
e.g. wind speed propellor anemometer which wont spin (overcome static friction) until a certain threshold is met
…could also reach maximum above which propellor couldnt spin faster
durability
is it operational under less than ideal conditions
time constant
period in which instrument reacts to fluctuation to within 37% of new value
NCAR
National enter for atmospheric research
NPL
National Physics Laboratory
UK euivalent to NIST
IRGA
Infrared gas analyzer
ITS-90
International temperature scale 1990
IPTS-68
International Practical Temperature Scale 1968
Thermocouple principles
Seebeck: voltage gradient proportional to temp gradient
Peltier Effect: current through dissimilar metals creates HEAT
Thermistors
Semiconductors: resistance temperature devices
- resistance decreases with temperature
- band gap
Conductors: resistance increases with temp
Thermal radiometers
Radiation heats sensor: Temperature difference between (heavy) base (reference) and sensor is measured.
Semiconductors: radiation in photon causes electrons to jump band gap
Time response equation
(T_inf - T(t)) / (T_inf - T_initial) = exp(-t/Tau)
Error propogation (Systematic)
Systematic:
Total Error F (delta F) =
= (partial F w.r.t. measurment 1)(error in 1) +
(partial F w.r.t. measurment 2)(error in 2) +…
Error propogation (random)
(Random error of F (sigma F)) =
= sqrt( (partial F w.r.t. var 1 × random error in var 1 )’2 + …….)
