Topic 2a: Clouds and Convection Flashcards
How does Radar work?
signal is reflected off hydrometers (raindrops. Reflectivity can be related to a surface rain rate
How does a visible satellite work?
reflected light in visible part of the spectrum. shows low clouds well but is useless at night
How does an infrared satellite work?
emitted light in thermal wavelengths, cant distinguish low clouds./fog well. cant determine height of cloud tops from temperature
what is the relationship between temperature and infrared radiation?
E ~ T^4
higher clouds are colder and therefore emits less energy. low clouds are warmer and emit more energy
if gamma e > gamma s what is the stability for saturated ascent?
unstable to saturated ascent
if gamma e = gamma s what is the stability for saturated ascent?
neutral to saturated ascent (moist neutral)
if gamma e < gamma s what is the stability for saturated ascent?
stable to saturated ascent
What is convection?
vertical mixing in the atmosphere
At which point does condensation occur?
from the LCL
How do deeper clouds form?
reach the LCL and condense. the latent heat release provides buoyancy. buoyancy accelerates parcels vertically. till the Equilibrium Level
What is conditional instability?
when an external force does work to allow instability (surface heating, sea breeze or mountain). when Ts<Td
Define Convective Inhibition (CIN)
Total negative area of the graph. amount of work that must be done to lift the parcel to its level of free convection.
Define Convective Available Potential Energy (CAPE)
Total positive area of the graph. Energy available to accelerate a parcel from its LFC to the EL.
What indices can be used to calculate thunderstorm potential and intensity?
1.
2.
3.
- Lifted Index (LIFT) = T500 - Tparcel
- Showalter (SHOW) = T500 - Tparcel
- Totals-Totals (TOTL) = (T850-T500) +(Td850-T500)
