Je vaporise tant que l’humidité ambiante reste basse.

French only elides je to j’ before a vowel sound or a silent h.

• je aime → j’aime
• je habite → j’habite
• but je vaporise stays je vaporise because v is a consonant sound

So Je vaporise is the correct full form.

Yes. Vaporise is the French verb vaporiser in the je form of the present tense.

It is closely related to English vaporize / vaporise, but in French it often means things like:

• to spray
• to mist
• to atomize
• to turn into vapor, depending on context

So in this sentence, Je vaporise most likely means I spray or I mist, not necessarily I turn something into gas in a scientific sense.

Tant que means as long as or while, depending on context.

In this sentence, it means:

• as long as the ambient humidity remains low

It introduces a condition that continues over time. The action in the main clause keeps happening during the period when the condition is true.

So:

• Je vaporise tant que... = I spray as long as...

It is a very common French expression.

No. They are related, but not the same.

• tant que = as long as / while in the sense of duration tied to a condition
• pendant que = while / during the time that
• alors que = whereas / while often with contrast

Examples:

• Je vaporise tant que l’humidité reste basse.
  = I spray as long as the humidity stays low.

• Je vaporise pendant que tu mesures la température.
  = I spray while you measure the temperature.

• Je vaporise, alors que lui attend.
  = I spray, whereas he waits.

So tant que is the best choice here because the idea is conditional duration.

Here, rester means to remain or to stay.

• reste is the il/elle/on present-tense form of rester
• the subject is l’humidité ambiante, which is singular, so the verb must also be singular

So:

• l’humidité ambiante reste basse
  = the ambient humidity remains low

French often uses rester where English might use stay or remain.

Because basse agrees with humidité, which is a feminine singular noun.

• un niveau bas → masculine singular
• une humidité basse → feminine singular

Here:

• humidité is feminine
• so the adjective must also be feminine: basse

This is standard adjective agreement in French.

Ambiante means ambient or surrounding.

So l’humidité ambiante means:

• the ambient humidity
• the humidity in the surrounding environment

It comes after the noun because many French adjectives are placed after the noun, especially more descriptive or technical ones like ambiant / ambiante.

Compare:

• la température ambiante = room/ambient temperature
• la lumière naturelle = natural light
• l’air frais = fresh air

Not all adjectives go after the noun, but ambiante normally does.

Because humidité begins with a vowel sound, and la becomes l’ before a vowel.

So:

• la + humidité → l’humidité

This is called elision.

It helps French sound smoother in speech.

Other examples:

• la école → l’école
• le arbre → l’arbre

French often uses an article where English might sometimes omit one.

Here, l’humidité ambiante refers to the ambient humidity, meaning the humidity in the surrounding air as a known or relevant concept.

Using the article makes the noun phrase sound complete and natural in French.

Without the article, humidité ambiante would usually appear in more technical labels, headings, or dictionary-style phrases, not as naturally in a normal sentence.

So:

• l’humidité ambiante reste basse = natural full sentence
• humidité ambiante = more like a category or label

Because tant que normally takes the indicative when it refers to a real situation or a condition presented as factual within the sentence.

Here, the speaker is talking about a practical condition:

• I spray as long as the ambient humidity remains low

So reste is present indicative.

French uses the subjunctive after some conjunctions, but tant que does not usually trigger it in this kind of statement.

Yes, it is in the present tense:

• Je vaporise
• reste

In French, the present tense can mean different things depending on context:

1. right now / currently

   • I am spraying as long as the humidity stays low.

2. habitually / generally

   • I spray whenever the ambient humidity remains low.

3. instructional or procedural style

   • I spray as long as the ambient humidity remains low.

So the exact nuance depends on the situation, but grammatically it is the present tense.

A careful pronunciation would be approximately:

Zhuh va-po-reez tan kuh loo-mee-dee-tay ahm-byant rest bahs

A few useful notes:

• Je sounds like zhuh
• vaporise sounds roughly like va-po-reez
• tant que is roughly tan kuh
• l’humidité has the stress pattern typical of French, ending around -té
• ambiante is roughly ahm-byant
• reste sounds like rest
• basse sounds like bahs

Also note the linking and flow:

• l’humidité ambiante is said smoothly as one group

Possibly, depending on what you mean.

• vaporiser often suggests spraying in a fine mist
• pulvériser can also mean to spray, but it may sound more technical, forceful, or like dispersing liquid into droplets
• pulvériser can also mean to crush to powder or even figuratively to destroy / smash

So if you mean a gentle misting or humidifying action, vaporise may fit better. If the context is more technical or mechanical spraying, pulvérise could also work.

The best choice depends on the exact situation.

It has two main parts:

1. Je vaporise
   = main clause

2. tant que l’humidité ambiante reste basse
   = subordinate clause expressing duration/condition

So the pattern is:

main action + tant que + condition that continues

You can model other sentences on it:

• Je continue tant qu’il fait jour.
  = I continue as long as it is daylight.

• Nous attendons tant que la porte reste fermée.
  = We wait as long as the door remains closed.

This makes the sentence a useful pattern to learn.