Section 1: Weather in the Air Book: Weather and Climate

What you need to be able to do! Develop a model to describe the cycling of water through Earth’s systems driven by energy from the sun and the force of gravity.

The Water Cycle Water Cycle: The continuous movement of water from water sources, such as lakes and oceans, into the air, onto and over land, into the ground and back to the water sources. Water continually cycles among land, ocean, and atmosphere via transpiration, evaporation, condensation and crystallization, and precipitation, as well as downhill flows on land. Global movements of water and its changes in form are propelled by sunlight and gravity.

The Water Cycle Water can exist in the air as a solid, liquid or gas. Solid-Ice is found in clouds as snowflakes. Liquid-water exists in clouds as water droplets. Gas-exists in air as water vapor

Condensation: Occurs when water vapor cools and changes back into liquid droplets. This is how clouds form.

Evaporation Occurs when liquid water changes into water vapor, which is a gas

Transpiration Is the process by which plants release water vapor into the air through their leaves

Precipitation Occurs when rain, snow, sleet, or hail falls form the clouds onto the Earth’s surface.

Runoff Is water, usually from precipitation, that flows across land and collects in rivers, streams and eventually the ocean.

Water Cycle Videos https://www.youtube.com/watch?v=al-do-HGuIk https://www.youtube.com/watch?v=YswL4dIDQuk

What you need to be able to do! Collect data to provide evidence for how the motions and complex interactions of air masses result in changes in weather conditions.

Weather Weather: is the condition of the atmosphere at a particular time. It is defined by temperature, Pressure, humidity, precipitation and wind.

Humidity: Humidity: is the amount of water vapor or moisture in the air. As water evaporates, the humidity of the air increases Air’s ability to hold water vapor depends on air temperature. As temperature increases, the air’s ability to hold water also increases. Humidity and its moisture in the air is what makes your hair go crazy!

Relative Humidity: Relative Humidity: is the amount of moisture the air contains compared with the maximum amount it can hold at a particular temperature. It is given as a percentage. Saturated: when air holds all the water it can at a given temp. Relative Humidity would be 100% How to Predict Humidity: Present/Saturated X 100 = Relative Humidity %

Example Relative Humidity Problem: Suppose that 1m³ of air at a certain temp can hold 24g of water vapor. However, you know that the air actually contains 18g of water vapor. Predict relative humidity. (Present) 18g/m³/(saturated)24g/m³ X 100 = (relative humidity) 75%

Condensation: Condensation: is the process by which gas, such as water vapor, becomes liquid. Before condensation can occur the air must be saturated or the relative humidity must be 100%. Condensation occurs when saturated air cools further. Condensation occurs when the air next to the glass cooled to below its dew point.

Dew point: Dew point: is the temperature to which air must cool to be completely saturated. The ice in the glass of water cause the air surrounding the glass to cool to its dew point.

Precipitation: Precipitation: is the water in solid or liquid form that falls from the air to the Earth. 4 Major Forms of Precipitation: Rain Snow Sleet Hail

Rain: Rain: is the most common form of precipitation. It is liquid water that falls from the clouds to Earth A cloud produces rain when its water droplets become large enough to fall. A water droplet start as the size of a period it must increase about 100x its normal size before it falls.

Snow Snow: is solid Precipitation forms when temps are so cold that water vapor changes directly to a solid.

Sleet: Sleet: is solid precipitation when rain falls through a layer of freezing air and turns to falling ice.

Hail: Hail: is solid precipitation that falls as balls or lumps of ice. It forms from updrafts of air in the clouds that carry rain drops to high altitudes in the clouds, where they freeze. This cycle can continue until the hail has many layers of ice. Eventually the hail becomes to heavy and falls to Earth.