1: air
1: atmosphere
1: cold
1: condition
1: Earth
1: heat
1: hot
1: moisture
1: move
1: pressure
1: rain
1: surface
1: temperature
1: troposphere
1: water
1: weather
1: weight
1: wind
2: big
2: bit
2: cloud
2: condensation
2: cool
2: drizzle
2: drop
2: dust
2: evaporation
2: float
2: fog
2: freeze
2: gas
2: ground
2: hail
2: heavy
2: invisible
2: join
2: particle
2: precipitation
2: rain
2: sleet
2: snow
2: sun
2: tiny
2: water
2: water cycle
2: water vapor
3: above
3: air
3: cold
3: Earth
3: heat
3: hot
3: land
3: measure
3: planet
3: ray
3: source
3: sun
3: sunlight
3: surface
3: temperature
3: warm
3: water
4: air
4: air pressure
4: airplane
4: change
4: difference
4: ear
4: Earth
4: feel
4: inside
4: storm
4: surface
4: weather
4: weight
5: above
5: air
5: area
5: blow
5: boat
5: branch
5: cool
5: Earth
5: face
5: feel
5: heat
5: sunlight
5: surface
5: tree
5: warm
5: wind
3: source
A source is the place from which something originates. For example, a battery is a source of energy.