Weather Flashcards
What is the make up of the Earth’s Atmosphere?
78% Nitrogen, 21% Oxygen and 1% other gases.
What are the atmospheric levels?
Troposphere, Stratosphere, Mesosphere, Thermosphere.
What is the tropopause?
The thin layer of atmosphere at the top of the tropopause that seals in most water vapor.
What is the major force that sets the atmosphere in motion?
Uneven heating
What is convection?
The circulating motion that results when warm air rises and is replaced by cooler air.
What is Coriolis?
A deflective force created by the difference in rotational velocity between the equator and the poles.
What are the four major types of pressure systems?
High, Low, ridge and trough.
What direction does wind move because of pressure gradient?
From areas of high to low pressure.
What is a Katabatic Wind?
Any wind blowing down an incline, they occur when cold dense air spills over a mountain and flows down the slope displacing the air ahead of it.
What are the three states in which water is found in the atmosphere?
Solid, liquid and gas.
What are the processes by which water can change it’s state?
Evaporation, sublimation, condensation, freezing, and melting.
What is evaporation?
The changing of liquid water to invisible water vapor.
What is condensation?
The changing of water vapor to liquid.
What is sublimation?
Changing of ice directly to water vapor or water vapor to ice…skipping the liquid state.
What is Relative Humidity?
The actual amount of moisture in the air compared to the total amount that could be present at that temperature.
What is dewpoint?
The temperature at which air reaches a state where it can hold no more water. When reached the air contains 100% of the moisture it can hold at that temperature and is saturated.
What are condensation nuclei?
Very small droplets of water or if temperature is low enough ice crystals that form clouds.
At what temperature/dew point spread is the air reaching it’s saturation point?
4 degrees F and 2 degrees C.
What is stability?
The atmosphere’s resistance to vertical motion.
What is a major factor to the stability of air?
Temperature
When do you see the greatest instability?
When air is both warm and moist.
What is adiabatic heating or cooling?
change in air temperature during expansion or compression of air, with no heat being added or removed from the air.
What is the formula for calculating cloud bases?
Surface Temp - Surface Dew point / 4.5 x 1000
What is a stationary front?
The front that separates two opposing forces of air masses that are relatively balanced.
