The present condition of the atmosphere is called weather and can be described by the following weather variables: Temperature Air Pressure Humidity Wind Clouds Precipitation

Temperature Temperature is the average kinetic energy of a substance. Kinetic energy is the energy of motion, so in the atmosphere: The more the gas molecules move (or VIBRATE), the more kinetic energy they have and the higher the air temperature. Where does the atmosphere get its energy?

Temperature There are three temperature scales: Celsius Fahrenheit Kelvin There is a temperature conversion chart on page 13 of your ESRT. Turn there now and convert these temperatures. 20 °F = ? °C 50 °C = ? K 273 K = ? °C and °F 20 °F = -7 °C 50 °C = 323 K 273 K = 0°C and 32°F

Temperature Meteorologists find it useful to map temperatures so they can see trends and make better forecasts. They draw lines on maps to connect equal temperatures called: Isotherms (type of Isolines)

How to make Isotherms or any type of isoline. 1. Realize exactly what temperature you looking to draw an isotherm for and make a “mark”on that number. Draw two isotherms at 10° intervals starting with 40 °F.

How to make Isotherms or any type of isoline. 1. Realize exactly what temperature you looking to draw an isotherm for and make a “mark”on that number. 2. Connect equal temperatures at the requested interval. Draw two isotherms at 10° intervals starting with 40 °F.

How to make Isotherms or any type of isoline. 1. Realize exactly what temperature you looking to draw an isotherm for and make a “mark”on that number. 2. Connect equal temperatures at the requested interval. Draw two isotherms at 10° intervals starting with 40 °F.

How to make Isotherms or any type of isoline. 1. Realize exactly what temperature you looking to draw an isotherm for and make a “mark”on that number. 2. Connect equal temperatures at the requested interval. Draw two isotherms at 10° intervals starting with 40 °F.

Do the Isotherm example in your notes. 1. Realize exactly what temperature you looking to draw an isotherm for and make a “mark”on that number. 2. Connect equal temperatures at the requested interval. Draw isotherms at 10° intervals.

Do the Isotherm example in your notes. 1. Realize exactly what temperature you looking to draw an isotherm for and make a “mark”on that number. 2. Connect equal temperatures at the requested interval. Draw isotherms at 10° intervals.

Air pressure is the weight of the atmosphere pushing down on the earth’s surface. This weight or pressure is affected by factors such as temperature and humidity. Cold temperatures lead to low kinetic energy and closely packed molecules (more dense = high pressure) Warm temperatures lead to high kinetic energy and widely spaced molecules (less dense = low pressure) Air Pressure

Barometer

Isobars Isobars connect equal air pressures on a map. They work the same way as isotherms and you should use the same techniques when drawing them. The white lines below are isobars. The “L” indicates low pressure and the “H” indicates high pressure.

1000  990  1010  1000  990  980  1020  980    990  1020  1000  980  1020  1010  990  1010  1000  990  990  In your notes, draw five isobars at 10mb intervals.

1000  990  1010  1000  990  980  1020  980    990  1020  1000  980  1020  1010  990  1010  1000  990  990  Start by marking one value like 980.

1000  990  1010  1000  990  980  1020  980    990  1020  1000  980  1020  1010  990  1010  1000  990  990  Then, connect the points with a smooth line.

1000  990  1010  1000  990  980  1020  980    990  1020  1000  980  1020  1010  990  1010  1000  990  990  Repeat this process for the next value (990).

1000  990  1010  1000  990  980  1020  980    990  1020  1000  980  1020  1010  990  1010  1000  990  990  Repeat this process for the next value (990).

1000  990  1010  1000  990  980  1020  980    990  1020  1000  980  1020  1010  990  1010  1000  990  990  Finally, it should look like this.

Humidity (aka water vapor) Air is saturated, when it is holding all the water vapor it can. When air temperature falls below it’s dew point temp., water vapor will turn into liquid. What is this process called?? Answer this in your notes, which has more water vapor? A parcel of air at 25°C and RH=70% or a parcel of air at 45°C and RH=70%. Please attempt to support your answer. Condensation! The higher the air temp. the more water vapor it can hold.

Measuring Humidity When it comes to forecasting precipitation, dew point temp. and relative humidity are critical. A sling psychrometer and page 12 of your ESRT allow us to determine dew point temp. and relative humidity. Attempt to explain why the wet-bulb temperature is always lower than the dry-bulb temperature? When evaporation occurs, it cools the surface of whatever the liquid is on.

Calculating Dew Point Temp. and Relative Humidity -

Cloud Formation What is a cloud? A cloud is a mass of air that has suspended water droplets and or ice crystals within it. What is fog? Fog is a low lying cloud.

Cloud Formation How do clouds form? 1 st Air must rise. 2 nd As air rises, the mass of air will experience Less air pressure aloft. This will allow the mass Of air to expand and when gases expand, they Cool (decrease in temperature). 3 rd If the decreasing temperature reaches its Dew point temp., condensation will occur (the Water vapor will turn to liquid). A CLOUD IS BORN!

Cloud Formation Windward side of Mtn. Leeward side of Mtn Mass of Air Prevailing Wind direction

Cloud Formation Windward side of Mtn. Leeward side of Mtn Mass of Air Prevailing Wind direction Air rises

Cloud Formation Windward side of Mtn. Leeward side of Mtn Mass of Air Prevailing Wind direction Air expands due to less pressure aloft

Cloud Formation Windward side of Mtn. Leeward side of Mtn Mass of Air Prevailing Wind direction Expands due to less pressure aloft.

Cloud Formation Windward side of Mtn. Leeward side of Mtn Mass of Air Prevailing Wind direction Expansion causes air to cool.

Cloud Formation Windward side of Mtn. Leeward side of Mtn Mass of Air Prevailing Wind direction When temp. reaches its dew pt. Temp., Condensation occurs.

Cloud Formation Windward side of Mtn. Leeward side of Mtn Prevailing Wind direction A cloud is Born!

Cloud Formation Windward side of Mtns. are Cool and Moist climates. Leeward side of Mtn Prevailing Wind direction A cloud is Born!

Cloud Formation Windward side of Mtn. Leeward side of Mtn Prevailing Wind direction

Cloud Formation Windward side of Mtn. Leeward side of Mtn Prevailing Wind direction Air mass will sink.

Cloud Formation Windward side of Mtn. Leeward side of Mtn Prevailing Wind direction Air will be compressed by increasing air pressure and air temp. will increase

Cloud Formation Windward side of Mtn. Leeward side of Mtn Prevailing Wind direction The difference between air temp. and dew pt. temp. will become greater and cause relative humidity to decrease.

Cloud Formation Windward side of Mtn. Leeward side of Mtns. are warm and dry climates. Prevailing Wind direction