weather – the condition of the outside air or atmosphere at a particular time and place.
climate - the average weather conditions over a very long period of timeo The climate of a region will also
determine the type of plants that grow there and the types of animals that live there.
cloud – a mass of tiny water droplets or ice crystals in the airowater vapor must lose heat energy before
clouds can form
Types of Clouds
1.cirrus clouds - thin wispy clouds that form high in the skyo form when wind is strongo if they get bigger and thicker, it's an indication of a
change in weather
2.stratus clouds - flat, horizontal clouds that form in layers. o form when a large mass of air is gently lifted into
the atmosphere.o usually form at low altitudes and cover large areas
of the sky.o tend to block out sunlight.o Fog is a stratus cloud that forms near Earth's
surface.o might bring light mist or drizzle
3.cumulus clouds - fluffy, white clouds that look like pieces of cotton balls with flat bottomso form as warm air rises and are usually a sign of fair
weather.
4.cumulonimbus clouds o can cause lightning, thunder, hail, strong rains,
strong winds, and tornadoeso have a dark base; towers in the skyo can be found from near the ground to up to 75,000
feet
****Clouds that bring precipitation usually start with nimbo or end with nimbus
High Clouds - form above 18,000 feet cirrus cirrocumulus cirrostratus
Middle Clouds - form between 6,500 feet to 18,000 feet altocumulus altostratus
Low Clouds - form below 6,500 feet stratus stratocumulus nimbostratus cumulus
Weather Instruments
rain gauge – measures the amount of rain
wind vane – shows wind direction – where the wind is coming from
anemometer – measures wind speed
barometer – measures air pressure
hygrometer – measures the amount of water vapor in the air – the humidity
AIR PRESSURE – the weight of the atmosphere pressing at a certain place
Air pressure can also tell us about what kind of weather we might have. Changes in air pressure mean that the weather is about to changeo HIGH PRESSURE = fair weather o LOW PRESSURE = rainy or stormy weather
Air pressure has the greatest effect on wind speed.
Air pressure changes depending on the altitude.oHIGHER ALTITUDE = Decreased air
pressureo LOWER ALTITUDE = Increased air
pressure(This is why your ears "pop" when you are riding in an airplane or driving high into the mountains)
air mass - a large body of air that has the same temperature and level of humidity throughout
front - the area in which two air masses meet
cold front - forms when a cold air mass moves under a warm air mass and causes the warm air mass to rise.o brings heavy rains, thunderstorms, and
sometimes snowo temperature drops when cold front passes
over an area
warm front - forms when a warm air mass meets a cold air mass and slowly rises over ito brings rainy, drizzly weather conditions o after a warm front passes over an area, the
temperature rises
occluded front - forms when a warm air mass is caught between two cold air masses.o brings cool temperatures and lots of rain and
snow
stationary front - occurs when a warm air mass and a cold air mass meet, but neither front has enough energy to push against the othero brings many days of overcast, rainy weather
Earth’s Three Climate Zones tropical zone – found near the equator; areas in
this zone get the most energy from the sun so they tend to be warm to hot all year
temperate zone – found between the polar and tropical zones; these areas tend to have seasons with very different temperatures
polar zone – found at the Earth’s North and South Poles; areas in this zone get the least energy from the sun, so they tend to be cool to cold all year.
Types of Air Masses
Moisture content is noted by the first letter. m = maritime = wet c = continental = dry
Temperature is noted by the second letter P = polar = cool T = tropical = warm
Maritime Tropical - mTo Warm and humido Originates closer to the Tropics over water
Maritime Polar - mPo Cold and dampo Originates in the Poles over water
Continental Tropical - cTo Warm and dryo Originates closer to the Tropics over land
Continental Polar - cPo Cold and dryo Originates closer to the Poles over land
Global Winds current – a flow of air or water in a certain
direction the uneven heating of the earth’s surfaces causes
wind. as the warm air at the equator rises, large areas
of low air pressure form there at the poles, the air is cold so it sinks. Areas of
high pressure form there wind blows from areas of higher pressure toward
areas of lower pressure
jet stream – an air current in the upper atmosphere that flows from west to east
o fast flowing river of airo winds can range from 120-250 mpho can be thousands of miles long, a couple of
hundred miles across and a few miles deep. o responsible for transporting highs and lowso affects precipitation and temperatureso marks boundaries between massive air
masseso air to the south of the jet stream is warm.o air to the north of the jet stream is cold.
Coriolis Effect Makes moving objects appear to curve toward the right
in the northern hemisphere and toward the left in the southern hemisphere.
prevailing westerlies winds that blow from the west to the east and move
toward the poles and are between 30 and 60 degrees latitude
responsible for many of the weather movements across the United States and Canada.
called prevailing westerlies because they’re named from the direction where they form
polar easterlies Form when the atmosphere over the poles cools. This
cool air then sinks and spreads over the surface. As the air flows away from the poles, it is turned to the west by the Coriolis effect. Because these winds begin in the east, they are called easterlies
trade winds air movements toward the equator. warm, steady breezes that blow almost continuously. Coriolis Effect makes the trade winds appear to be
curving to the west, whether they are traveling to the equator from the south or north.
doldrums a region of the ocean near the equator where there is
little or no wind
Breezes
sea breeze – the movement of air caused by cool air over the ocean moving toward the lando occurs during the dayo land temperature near the beach is rising
more rapidly than the ocean temperature
land breeze – the movement of air created by cool air over land moving toward the ocean o occurs at nighto land quickly loses heat at night; water
retains heat so the air over water is warmer, less dense and begins to rise
Ocean Currents Warm currents from tropical areas carry warm
water near the coastlines of cooler areas. The warm water helps keep land near the coastlines warm
Cold water currents from the poles travel toward the equator. The cold water brings cooler temperatures to some coastlines in those areas
Gulf Stream – a warm ocean current in the Atlantic Ocean flows northeast along the eastern coast of the US moves warm waters out across the Atlantic Ocean,
then towards the north keeps weather along the eastern coast mild by
warming the air and land there during the cooler months
Radiation from the sun warms the waters of the Gulf Stream. Then the water warms the air above it – warms coastal land over which it moves
El Nino – an unusual warming of the surface water in the eastern Pacific Ocean near the equator
usually brings more rain and higher temperatures causes rising surface temperatures of the Pacific
Ocean, drought in the western US and flooding on the Pacific coast of South America.
La Nina – an unusual cooling of the surface water in the eastern Pacific Ocean near the equator
