Weather

Atmospheric layers Troposphere – weather occurs here, closest to ground, colder as you rise; ends with the tropopause. Stratosphere – jet stream here; from tropopause up warmer as you rise; ozone layer is here. Ends with stratopause. Mesosphere – ice clouds that burn up meteoroids; from stratopause up , colder as you go up. Ends with mesopause. Thermosphere – hot layer, made of two layers. Ionosphere where satellites and auroras are; and Exosphere marking the end of the atmosphere at 800 km.

Review 13: Weather Meteorologist – scientists who study the weather. What direction do most weather systems travel in the U.S.?

Defining weather… Weather is the daily conditions of the atmosphere

Heat Energy and the Atmosphere The Sun’s energy is mostly absorbed by the Earth but some is reflected back into space

The Greenhouse Effect Caused by the increased amount of CO2 which is placed there through burning fossil fuels.

arctic cod Krill?, amphipods? amphipod black guillemot copepod

harp seal bearded seal ribbon seal walrus spotted seal ringed seal hooded seal

GREENHOUSE EFFECT

Air pressure Air pressure if the force of air pressing down on the Earth’s surface Highest at sea level. As elevation increases (you go up) pressure and density decreases (air is thinner).

Air Masses A large body of air that has properties similar to the part of the Earth’s surface over which it develops.

Air Mass Map

Fronts A boundary between two air masses of different density, moisture, or temperature.

Cold Front

Warm Front

Occluded Front

Stationary Front

Severe Weather occurs when two different fronts collide. Thunderstorms Lightning Tornadoes

How do storms begin?

Types of storms… Storms –violent disturbance in the atmosphere. Marked by sudden change in air pressure and rapid air movement; two different fronts collide (warm meets cold)

Winter weather…

Thunderstorms Thunderstorms – cold meets warm front.

Cyclones and Anticyclones? Cyclones – area of low pressure that cause rainy stormy weather. Anticyclones – high pressure area that causes dry clear fair weather.

Hurricanes and Typhoons are the same thing…

More about tornadoes… Great Plains – “tornado alley”. Average diameter - .4 km Length traveled – 6 km for only a few minutes but winds can still reach more than 350 km/hour.

More Severe Weather Hurricanes Blizzards

Severe Weather Safety Watches- conditions are favorable Warnings- conditions already exist Examples- Tornadoes, Flooding, Thunderstorms, Blizzards, Winter Mixes and Hurricanes

Lightning – opposites attract Lightning – opposites attract. Will strike the tallest positively charged object.

Tornado Alley

Fujita Scale

Hurricane

Saffir-Simson Scale measures Hurricanes

NWS Two sources of forecasting weather Data collected from upper atmosphere Data collected on the Earth’s surface

Weather Station Model

Isobars Isobars-connect points of the “same” Examples: temperature and wind speed The further away the lines the lower the wind speed

Winds Wind is caused by unequal heating of the atmosphere Winds travel from high to low pressure Winds curve to the right in the N hemisphere and to the left in the S hemisphere called the Coriolis effect

Local winds blow in all directions and in short distances. Land and Sea breezes Local winds blow in all directions and in short distances. You feel the air moving from water to land during the day Warm air rises over the land and moves over the water Cool air sinks and travels toward the land You feel the air moving from land to the water at night Warm air rises over the water and moves toward the land Cool air sinks toward the land

Jet Stream jet stream - strong, high speed wind that blows from west to east. Located in the stratosphere.

Moisture in the Air Humidity - Water vapor or moisture in the air. Dew Water – water vapor becomes liquid water as it condenses. Condensation forms clouds as water vapor rises and cools.

MOISTURE

Weather High-pressure system – when cold air sinks to the ground, warms up, and absorbs water vapor, causing sunny skies. Low-pressure system – when warm air rises higher in the sky, causing water vapor to cool and form clouds and precipitation. Predict what will happen if a high-humidity air mass located over an ocean moves inland and up a mountain slope. Why do you think so?

Movement of Pressure Systems High Pressure moves clockwise and outwardly. Low Pressure moves counterclockwise and inwardly.

Cirrus – highest clouds Indicate rain/snow in next 24 hours Cumulus – bright white wads of cotton seen with fair weather

More on clouds Stratus – form gray sheets that spread across the sky Bring heavy mist, snow or drizzle. Cause fog. Cumulonimbus – largest clouds. Bring heavy rain, high winds, hail and tornadoes. Describe the clouds you see outside. Do they fit any of the categories?

Precipitation types Hail – when a raindrop freezes and forms an icy ball before falling to the ground. Sleet – when a raindrop falls from a cloud and passes through below-freezing air making a slushy blob. Snow – when ice crystals form in clouds and fall to the ground without melting.

Weather Make a prediction. What kind of precipitation will fall if there are: Below-freezing temperatures in the clouds Temp. barely above freezing on the ground? Describe the air temperature, precipitation, winds, and humidity during: Winter? Spring? Summer? Fall?

Weather Wind speed is described in miles per hour. Wind direction is the direction from which the wind blows. A north wind comes from the north. The tail points to where the wind is coming from. The barbs on the tail show the speed of the wind. More barbs – faster wind The dot points to the direction the wind is going.

Tools to gather data about the weather: Review 13: Weather Tools to gather data about the weather: Thermometer – measures temperature Anemometer – measures wind speed

Tools to gather data about the weather: Review 13: Weather Tools to gather data about the weather: Rain Gauge – measures the amount of precipitation Barometer – measures air pressure Weather Vane – indicates wind direction

Odd-shaped clouds

Even more…

Sun dogs

Weather Stations & Weather Map Symbols

Temperature Top left number shows the temperature

Weather Symbol The symbol between the two numbers on the left indicate what the weather is in terms of precipitation.

Notice how more symbols indicate intensity More snow flake symbols =more snow More rain symbols = heavy rain

The number on the bottom left shows the temperature the air must be for condensation to occur or the Dew Point. Humidity is a factor of the dew point. This number will be lower than the actual temperature. Remember cold air can’t hold moisture like warm air Dew Point

Cloud Cover The percentage of the circle that is shaded in reflects the percentage of cloud cover in the sky Similar to a pie chart

Air Pressure This number is displayed on the top right of the weather symbol When the # is high or rising, the weather is fair because the pressure is high When the # is low or dropping, the weather is rainy, because the pressure is low

Wind Barb This shows the direction of the wind, it will point in the direction the wind is coming from, this shows the wind coming from the Southeast The # of lines and/or triangles indicates the speed of the wind

The wind barb points in the direction it is coming FROM. Stronger winds have more flags, or marks

Fronts on a weather map Warm occluded Cold Stationary The symbols point in the direction that the front is moving towards Pressure symbols:

Isobars: connect areas with equal air pressure The distance between the isobars is called the pressure gradient The closer the isobar lines, the greater the change in air pressure, and the greater/faster the winds speeds. High pressure systems bring clear/sunny weather and wind flows out and clockwise (right) Low pressure systems bring overcast/stormy weather and wind flows in and counter-clockwise (left)