Weather

&

Climate and Climate Change

(Study guide for test)

Words to know:

Meteorology- The study of weather Weather- The state or condition of the atmosphere at a particular

location for a short period of time Climate- Average of weather conditions in a region over a long

period of time Atmospheric Variables- Ever-changing factors that affect and

change weather Humidity- The amount of moisture in the air (water vapor)

o Absolute Humidity- The total mass of water vapor in a given volume of air. Depends on temperature. The higher the temperature, the more water vapor the air can hold.

o Relative Humidity- The amount of water vapor in the air relative to the amount of water vapor that the air can hold.

o Instrument: Sling Psychomotor Temperature- The average kinetic energy of particles in a

substance. Instrument: thermometer.o Adiabatic Cooling- Air is forced up by the mountain and

expands because of less pressure and it cools off. *Cools due to Expansion*

Air Pressure- The pressure of the air pushing down on a surfaceo High Pressure Center- dry, clear and cooler (air) weather.o Low Pressure Center- Wet, cloudy, warmer (air) weather.

Regional Winds- Winds that extend over a large area Local Winds- Winds that extend only for a few miles Pressure gradient- A difference in air pressure between 2 places Winds cause ocean currents

Meteorology

Atmospheric Variables:

1. Temperature2. Pressure3. Humidity4. Wind5. Precipitation6. Cloud Cover7. Dew Point Temperature

Station Models

(*Found on pg. 13 of ESRT*)Tells you where the wind is coming FROM

Tendency:

/ —— \

Increase Steady Decreasing

In °F Convert Barometric Pressure:

000-499, add 10 in front

500-999, add 9 in front

Put a decimal between last two digits

EX:

138=1013.8

Humidity

*Humidity increases as air temperature approaches dew point temperature

*The Drier the air, the more evaporation, the more cooling

(Dew point and Relative Humidity chart pg. 12)

Temperature

Factors that Affect Temperature:

Latitude: **The lower the latitude = the higher the

temperature**

Duration of Isolation: **The longer the sun is out = the higher the temperature**

Time of Day: **Hottest temperatures occur between 2-4 pm** Season: ** The hottest temperatures occur between July-Aug.**

Dry Bulb Temp.

In °C

Dry Bulb Temp.

In °C

Difference between Wet Bulb and Dry Bulb

In °C

Difference between Wet Bulb and Dry Bulb

In °C

HOT

COLD

COLD

= 0° latitude, Hottest

Altitude: **Higher altitude = Lower temperature**

Surface where air exists: **Color & Texture and Specific heat of substance**

Particulate Matter: **More aerosols = Cooler Temperature** Clouds: **Clouds- Day = Cooler Temperature & Clouds- Night =

Warmer Temperature**Air Pressure

Factors that affect air pressure: Density: the greater the density the greater the air pressure

because there are more air molecules in a given space Temperature: Colder the Temp, the higher the air pressure

because the air is denser Humidity: Moist air has a low air pressure because the

mass of moist air is less than the mass of dry air

High Pressure Center: pressure increases as you move into the pressure center.

Low Pressure Center: Pressure decreases as you move into the pressure center.

THE CLOSER THE ISOBARS THE FASTER THE WIND

Northern Hemisphere

Hottest in July and August

Inward and Counterclockwise

Outwards and Clockwise

Southern Hemisphere

Wind

Wind blows from High pressure to low pressure Steep pressure gradient- changes quickly, isobars are close

together, and wind speeds are high Gentle pressure gradient- changes slowly, isobars are widely

spaced and wind speeds are low Anemometer- used to measure wind speed Weather Vane- used to measure wind direction

Sea Breeze Land Breeze

Outwards and Counterclockwise

Inward and Clockwise

Prevailing Winds (found on pg. 14 of ESRT)

Monsoons: Seasonal changes in the direction of the prevailing winds. Similar to land and sea breezes but can last for months and move over a greater distance.

Jet Streams: Narrow bands of fast moving, high-altitude wind which separates the cold polar air from the warmer air in the South. They blow from WEST to EAST at about 200 mph.

Clouds

Cloud- a collection of tiny droplets of water or ice To form, water must evaporate from the ocean or from other

bodies of water

Factors that affect the rate at which a substance evaporates:

1. Degree of Saturation- if air is saturated, not much evaporation2. Surface Area- if water is spread out3. Wind Speed- faster winds evaporate water faster

Cloud Formation

1. Moist air is less dense so it rises2. Rising air expands and cools3. When rising air cools down to the dew point temperature, the

air becomes saturated and condensation occurs if condensation nuclei are present.

Air Masses

Air Mass- a large body of air with similar conditions of temperature, moisture, pressure, and winds throughout

Characteristics are determined by the geographical region of origin, its temperature and moisture

o Maritime (m): air that forms over water and is moist

o Continental (c): air that forms over land and is dry Polar (p): forms over cold regions Arctic (a): forms over very cold regions Tropical (t): forms over warm regions

An air mass generally moves toward the east over the U.S. because the U.S. is located in the Southwest wind belt

Fronts

Cold Front

Faster than warm fronts Brief, heavy precipitation followed by cooler temp.

o At the leading edge of the cold front

Warm Front

Light, steady rain and warmer temperatures

Stationary Front

A cold front and warm front are stuck at a standstill, can remain for days

Gentle, steady rain with lots of clouds that could last for days

Occluded Front

A cold front overtakes a warm fronto Because cold fronts move faster than warm fronts

Warm air is wedged between two cooler air masses and is forced up, cools due to expansion and it reaches its dew point and precipitation occurs

Long periods of gentle to heavy rain