Core

Core Weather Parameter	Definition	Calculations
Cloud Base Height (CBH)	CBH is an important characteristic linked to cloud type that describes the influence of clouds on the environment. Units are in meters or km.	NA
Cloud Top Height (CTH)	CTH is defined as that particular height abive the Earths surface at which cloud layer Terminates. Units in meters or Km.	NA
Cloud Top Temperature (CTT)	CTT is defined as the temperature at cloud top and is used to monitor cloud top chnages during convection. Units in Kelvin	NA
Cloud Top Pressure (CTP)	CTP is derived from CTT and is considered equivalent to cloud top height above mean sea level. Units hPa	P(CTP) = P(T=CTT) finding the pressure level at which temperature equals the cloud top temperature.
Cloud Fraction (CF)	CF represents the fractional area covered by clouds as observed from above by satellites.	It is estimated by counting the number of satellite fields-of-view (called pixels) that are determined to be cloudy and dividing by the total number of pixels in a region.
Cloud Types	Cloud Types - clouds are grouped by the altitude of their base and by their apperances	NA
Apparant Temperature	Temperature felt by human body (felt air temperature) Heat index is another term for apparant temperature. Units Kelvin	HI=T+0.33e−0.70−4.00, T = air temperature at 2m, e is vapour pressure e=RH×6.105×exp(237.7+T17.27T)/100
Dew point Temperature	Temperature at which air becomes satured with respect to water vapor, leading to condensation. Units Kelvin	Td = 237.7[ln(RH/100) + (17.27T/237.7 + T)]/17.27 - [ln(RH/100) + (17.27T/237.7 + T)]
Potential Temperature	Temperature that a parcel of dry air would attain if brought dry adiabatically to surface. Units Kelvin	θ = T(1000/p)^0.286
Virtual Temperature	Virtual Temperature is the temperature at which dry air would have the same density as the moist air, at a given pressure. Units Kelvin	Tv = T(1 + 0.61q), T = air temperature , q is specific humidity
Dew point depression	Difference between temperature and dewpoint temperature. Units (Kelvin)	T-Td
Relative Humidity	Ratio of the vapor pressure of water vapor in the air to the vapor pressure of water vapor when the air is saturated, expressed as a percentage	RH = (e/es) X 100%
Specific Humidity	Specific humidity focuses on the mass of water vapor compared to the total mass of the air parcel, including both dry air and the vapor. Units (g/Kg)	q = 0.622e/p-0.378e here e is vapour pressure. p = pressure level.
Mixing Ratios	Ratio of mass of water vapor to the maa of dry air in a volumn of air. Units g/Kg	r = 0.622 X (e/p - e), e is vapour pressure and p is air pressure
Sea Level Pressure	Sea level pressure refers to the atmospheric pressure at mean sea level, defined as 1013.25 hPa or 1 atm	NA
Surface Pressure	Atmospheric pressure at a given spot in Earth surface is known as surface pressure. Units hPa.	NA
Precipitation forms (Rain, Snow, Ice, Graupel, Hail)	Precipitation is a vital process in the Earth’s atmosphere, where water in liquid (Rainfall) or solid form (Hail, Ice, Snow, Graupel) falls from clouds and reaches the ground. Units mm/hr	NA
Wind Gust	Wind gust is the suddent burst of stronger winds. Units m/sec	NA
Storm Relative Helicity (SRH)	SRH is an indicator used to measure the potential of storm rotation. It is the rate of change of winds in a particular direction. Units m2/sec2	SRH=∫((v−cv)⋅(∂u/∂z)−(u−cu)⋅(∂v/∂z)))dz
Thunderstorm Probability (Energy Helicity Index)	Energy Helicity Index is a function of CAPE and storm relative helicity (SRH). No units dimensionless.	EHI = (CAPE X SRH)/160,000
Atmospheric Boundary Layer Height	Atmospheric Boundary Layer (ABL) height defines the volume of air within which heat, moisture and pollutants released at the Earth’s surface are rapidly diluted. Units m/Km	h≈1000+120Ts (Day time boundary layer, Ts is surface temperature).
Geopotential Height	Geopotential height (H) is a widely used metric for atmospheric circulation. Height of a pressure surface in the atmosphere by accounting for the variation of gravity with latitude and altitude. Units in m	H= Φ(z)/g0, Φ(z) is geopotential and g0 is standard gravity at sea level (9.8m/sec2)