Weather module 1 Flashcards
Describe the extent, circulation and characteristics of a low
Can vary greatly in size, and associated with cloudy weather. circulation is counter-clockwise
Pressure tendency is
The change with time of the pressure reported by a station.
What is radiation cooling?
At night, when radiation from the sun stops, the earth will continue to radiate its heat and become cooler. The air near the surface of the earth will give up its heat to the colder earth through conduction.
Define subsidence
The downward motion of air
What are the 2 adiabatic lapse rates?
Dry = 3 degrees/1000ft Saturated = 1.5 degrees/1000ft
Define lapse rate
The rate of temperature change with height
If air is forced to ascend it? (2)
expands and cools
List the 3 causes of pressure variation over time
- Movement of pressure systems
- Variation in intensity of systems
- Diurnal variations in pressure
If the atmospheric lapse rate is greater than the adiabatic lapse rate of a parcel of air the air is considered:
Unstable
What is the internation standard lapse rate?
1.98 degrees /1000ft
isobars on surface weather maps form:
pressure patterns
When air expands we say that ____ or _____ has occured
Expansion or Adiabatic cooling
What are the typical atmospheric conditions for stable air?
- Stratiform clouds
- Continuous or intermittent precip
- Fog
- reduced visibility
- Drifting snow
- Little turbulence
What happens to latent heat during the evaporation and condensation process.
The heat energy needed during evaporation is stored in the water molecule as “latent heat”.because there is a loss of energy there will be a cooling of the air. If air is cooled to the saturation point, the vapor will change state to a liquid and the latent heat will be transferred to the ambient air as sensible heat.
If there is no variation in temperature with altitude it is referred to as
Isothermal
give the 3 units of pressure measurement and state the standard pressure for each
1 Hectopascals 1013
- Kilopascals 101.3
- Inches of mercury 29.92
When air near the surface accumulates in a region, the excess air is forced to rise. what is this called?
Convergence
Describe the conditions under which to provide PBS
- Request from customer
- Specific request
- unsolicited information
- Foreign request
- AWWS assistance
Define Dew point
The temperature to which air would have to be cooled to achieve saturation.
Define Radiation
The process of heat energy transfer in the form of electromagnetic waves
List the 4 terms used when the central pressure is changing with low and high pressure systems
LOW 1.Deepening
2. Filling
High 1. Building
2. Weakening
List the 2 processes by which the atmosphere is cooled
- Radiation cooling
2. Advection cooling
What is the relationship between station pressure and elevation
The higher the station elevation, the lower the station pressure.
Define pressure gradient
The rate of change of pressure with horizontal distance